diff --git a/src/Twilio/TwiML/Fax/Receive.cs b/src/Twilio/TwiML/Fax/Receive.cs
index a30217243..88dee26f9 100644
--- a/src/Twilio/TwiML/Fax/Receive.cs
+++ b/src/Twilio/TwiML/Fax/Receive.cs
@@ -91,7 +91,7 @@ public Receive(Uri action = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Messaging/Message.cs b/src/Twilio/TwiML/Messaging/Message.cs
index 85ffda8eb..b0351532d 100644
--- a/src/Twilio/TwiML/Messaging/Message.cs
+++ b/src/Twilio/TwiML/Messaging/Message.cs
@@ -78,7 +78,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.To != null)
diff --git a/src/Twilio/TwiML/Messaging/Redirect.cs b/src/Twilio/TwiML/Messaging/Redirect.cs
index 2a7647caf..cdf2071da 100644
--- a/src/Twilio/TwiML/Messaging/Redirect.cs
+++ b/src/Twilio/TwiML/Messaging/Redirect.cs
@@ -49,7 +49,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Method != null)
diff --git a/src/Twilio/TwiML/Text.cs b/src/Twilio/TwiML/Text.cs
index 5efb4a6e6..cc6e401b7 100644
--- a/src/Twilio/TwiML/Text.cs
+++ b/src/Twilio/TwiML/Text.cs
@@ -1,4 +1,9 @@
-using System.Xml.Linq;
+#if !NET35
+using System.Threading;
+using System.Threading.Tasks;
+#endif
+using System.Xml;
+using System.Xml.Linq;
 
 namespace Twilio.TwiML
 {
@@ -15,5 +20,18 @@ protected override XNode ToXml()
         {
             return new XText(_content);
         }
+
+#if !NET35
+        protected override async Task WriteXml(XmlWriter writer, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            await writer.WriteStringAsync(_content).ConfigureAwait(false);
+        }
+#endif
+
+        protected override void WriteContent(XmlWriter writer)
+        {
+            writer.WriteString(_content);
+        }
     }
-}
+}
\ No newline at end of file
diff --git a/src/Twilio/TwiML/TwiML.cs b/src/Twilio/TwiML/TwiML.cs
index ec625992d..290c52caf 100644
--- a/src/Twilio/TwiML/TwiML.cs
+++ b/src/Twilio/TwiML/TwiML.cs
@@ -1,34 +1,28 @@
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
-using System.Text;
 using System.Xml.Linq;
-using Twilio.Exceptions;
 
 namespace Twilio.TwiML
 {
-
     /// <summary>
     /// Base class for all TwiML Objects.
     /// </summary>
-    public class TwiML
+    public partial class TwiML
     {
         /// <summary>
         /// Tag name
         /// </summary>
         private string TagName { get; }
+
         /// <summary>
         /// Children elements
         /// </summary>
         private List<TwiML> Children { get; }
+
         /// <summary>
         /// Additional tag attributes to set on the generated xml
         /// </summary>
-        private List<KeyValuePair<string,string>> Options { get; }
-        /// <summary>
-        /// Attribute names to be transformed on the generated xml
-        /// </summary>
-        private Dictionary<string, string> AttributeNameMapper = new Dictionary<string, string> { { "for_", "for" } };
+        private List<KeyValuePair<string, string>> Options { get; }
 
         /// <summary>
         /// Base constructor to create any TwiML instance.
@@ -36,9 +30,9 @@ public class TwiML
         /// <param name="tagName"> TwiML tag name </param>
         protected TwiML(string tagName)
         {
-            this.TagName = tagName;
-            this.Children = new List<TwiML>();
-            this.Options = new List<KeyValuePair<string,string>>();
+            TagName = tagName;
+            Children = new List<TwiML>();
+            Options = new List<KeyValuePair<string, string>>();
         }
 
         /// <summary>
@@ -52,9 +46,9 @@ protected virtual string GetElementBody()
         /// <summary>
         /// Get the TwiML element attributes.
         /// </summary>
-        protected virtual List<XAttribute> GetElementAttributes()
+        protected virtual IEnumerable<XAttribute> GetElementAttributes()
         {
-            return new List<XAttribute>();
+            return Enumerable.Empty<XAttribute>();
         }
 
         /// <summary>
@@ -63,13 +57,13 @@ protected virtual List<XAttribute> GetElementAttributes()
         /// <param name="childElem"> Child TwiML element to add </param>
         public virtual TwiML Append(TwiML childElem)
         {
-            this.Children.Add(childElem);
+            Children.Add(childElem);
             return this;
         }
 
         public TwiML AddText(string text)
         {
-            this.Children.Add(new Text(text));
+            Children.Add(new Text(text));
             return this;
         }
 
@@ -79,7 +73,7 @@ public TwiML AddText(string text)
         /// <param name="childElem"> Child TwiML element to add </param>
         public T Nest<T>(T childElem) where T : TwiML
         {
-            this.Children.Add(childElem);
+            Children.Add(childElem);
             return childElem;
         }
 
@@ -89,7 +83,7 @@ public T Nest<T>(T childElem) where T : TwiML
         /// <param name="tagName"> TwiML tag name </param>
         public TwiML AddChild(string tagName)
         {
-            return this.Nest(new TwiML(tagName));
+            return Nest(new TwiML(tagName));
         }
 
         /// <summary>
@@ -99,12 +93,12 @@ public TwiML AddChild(string tagName)
         /// <param name="value"> Option value </param>
         public TwiML SetOption(string key, object value)
         {
-            if (this.Options.Exists(e => e.Key.Equals(key)))
+            if (Options.Exists(e => e.Key.Equals(key)))
             {
-                this.Options.Remove(this.Options.Find(e => e.Key.Equals(key)));
+                Options.Remove(Options.Find(e => e.Key.Equals(key)));
             }
 
-            this.Options.Add(new KeyValuePair<string, string>(key, value.ToString()));
+            Options.Add(new KeyValuePair<string, string>(key, value.ToString()));
             return this;
         }
 
@@ -114,77 +108,7 @@ public TwiML SetOption(string key, object value)
         /// <param name="key"> Option key </param>
         public virtual string GetOption(string key)
         {
-            return this.Options.Find(e => e.Key.Equals(key)).Value;
-        }
-
-        /// <summary>
-        /// Generate XElement from TwiML object
-        /// </summary>
-        protected virtual XNode ToXml()
-        {
-            var elem = new XElement(this.TagName, this.GetElementBody());
-
-            this.GetElementAttributes().ForEach(attr =>
-            {
-                string transformedAttr = attr.Name.LocalName;
-                if (AttributeNameMapper.TryGetValue(attr.Name.LocalName, out transformedAttr))
-                {
-                    elem.Add(new XAttribute(transformedAttr, attr.Value));
-                }
-                else
-                {
-                    elem.Add(attr);
-                }
-            });
-
-            this.Options.ForEach(e =>
-            {
-                if (e.Key.StartsWith("xml:"))
-                {
-                    var attribute = new XAttribute(XNamespace.Xml + e.Key.Substring(4), e.Value);
-                    elem.Add(attribute);
-                }
-                else
-                {
-                    elem.Add(new XAttribute(e.Key, e.Value));
-                }
-            });
-
-            this.Children.ForEach(child => elem.Add(child.ToXml()));
-
-            return elem;
-        }
-        
-        /// <summary>
-        /// Generate XDocument from TwiML object
-        /// </summary>
-        public XDocument ToXDocument()
-        {
-            var declaration = new XDeclaration("1.0", "utf-8", null);
-            var elem = this.ToXml();
-            var document = new XDocument(declaration, elem);
-            return document;
-        }
-
-        /// <summary>
-        /// Generate XML string from TwiML object
-        /// </summary>
-        /// <param name="formattingOptions"> Change generated string format. </param>
-        public string ToString(SaveOptions formattingOptions = SaveOptions.None)
-        {
-            var document = this.ToXDocument();
-            var writer = new Utf8StringWriter();
-            document.Save(writer, formattingOptions);
-            return writer.GetStringBuilder().ToString();
+            return Options.Find(e => e.Key.Equals(key)).Value;
         }
     }
-
-    /// <summary>
-    /// StringWriter which overrides default encoding to use UTF8.
-    /// </summary>
-    public class Utf8StringWriter : StringWriter
-    {
-        public override Encoding Encoding => Encoding.UTF8;
-    }
-
 }
\ No newline at end of file
diff --git a/src/Twilio/TwiML/TwiMLSerializer.cs b/src/Twilio/TwiML/TwiMLSerializer.cs
new file mode 100644
index 000000000..5bf4818fb
--- /dev/null
+++ b/src/Twilio/TwiML/TwiMLSerializer.cs
@@ -0,0 +1,390 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Threading;
+using System.Xml;
+using System.Xml.Linq;
+using Stream = System.IO.Stream;
+#if !NET35
+using System.Threading.Tasks;
+using Task = System.Threading.Tasks.Task;
+#endif
+
+namespace Twilio.TwiML
+{
+    /// <summary>
+    /// Base class for all TwiML Objects.
+    /// </summary>
+    public partial class TwiML
+    {
+        /// <summary>
+        /// Attribute names to be transformed on the generated xml
+        /// </summary>
+        private static Dictionary<string, string> AttributeNameMapper = new Dictionary<string, string> { { "for_", "for" } };
+
+        /// <summary>
+        /// Generate XElement from TwiML object
+        /// </summary>
+        [Obsolete]
+        protected virtual XNode ToXml()
+        {
+            var elem = new XElement(TagName, GetElementBody());
+
+            foreach (var attr in GetElementAttributes())
+            {
+                string transformedAttr = attr.Name.LocalName;
+                if (AttributeNameMapper.TryGetValue(attr.Name.LocalName, out transformedAttr))
+                {
+                    elem.Add(new XAttribute(transformedAttr, attr.Value));
+                }
+                else
+                {
+                    elem.Add(attr);
+                }
+            }
+
+            Options.ForEach(e =>
+            {
+                if (e.Key.StartsWith("xml:"))
+                {
+                    var attribute = new XAttribute(XNamespace.Xml + e.Key.Substring(4), e.Value);
+                    elem.Add(attribute);
+                }
+                else
+                {
+                    elem.Add(new XAttribute(e.Key, e.Value));
+                }
+            });
+
+            Children.ForEach(child => elem.Add(child.ToXml()));
+
+            return elem;
+        }
+
+        /// <summary>
+        /// Generate XDocument from TwiML object
+        /// </summary>
+        [Obsolete("ToXDocument will be removed in the future. Please use ToString, Save, or SaveAsync.")]
+        public XDocument ToXDocument()
+        {
+            var declaration = new XDeclaration("1.0", "utf-8", null);
+            var elem = ToXml();
+            var document = new XDocument(declaration, elem);
+            return document;
+        }
+
+        /// <summary>
+        /// Write TwiML to TextWriter as XML.
+        /// </summary>
+        /// <param name="textWriter">TextWriter to write XML string to.</param>
+        public void Save(TextWriter textWriter)
+        {
+            Save(textWriter, SaveOptions.None);
+        }
+
+        /// <summary>
+        /// Write TwiML to TextWriter as XML.
+        /// </summary>
+        /// <param name="textWriter">TextWriter to write XML string to.</param>
+        /// <param name="formattingOptions">Change generated string format.</param>
+        public void Save(TextWriter textWriter, SaveOptions formattingOptions)
+        {
+            var ws = GetXmlWriterSettings(formattingOptions);
+            using (var writer = XmlWriter.Create(textWriter, ws))
+                Save(writer);
+        }
+
+        /// <summary>
+        /// Write TwiML to Stream as XML.
+        /// </summary>
+        /// <param name="stream">Stream to write XML string to.</param>
+        public void Save(Stream stream)
+        {
+            Save(stream, SaveOptions.None);
+        }
+
+        /// <summary>
+        /// Write TwiML to Stream as XML.
+        /// </summary>
+        /// <param name="stream">Stream to write XML string to.</param>
+        /// <param name="formattingOptions">Change generated string format.</param>
+        public void Save(Stream stream, SaveOptions formattingOptions)
+        {
+            var ws = GetXmlWriterSettings(formattingOptions);
+            using (var writer = XmlWriter.Create(stream, ws))
+                Save(writer);
+        }
+
+        /// <summary>
+        /// Write TwiML to XmlWriter as XML. Configure the XmlWriter before invoking Save.
+        /// </summary>
+        /// <param name="writer">XmlWriter to write XML string to.</param>
+        public void Save(XmlWriter writer)
+        {
+            writer.WriteStartDocument();
+            WriteContent(writer);
+            writer.WriteEndDocument();
+            writer.Flush();
+        }
+
+        /// <summary>
+        /// Write the Element, Attributes, and inner XML of this TwiML object.
+        /// </summary>
+        /// <param name="writer">XmlWriter to write XML string to.</param>
+        protected virtual void WriteContent(XmlWriter writer)
+        {
+            writer.WriteStartElement(null, TagName, null);
+
+            foreach (var attribute in GetElementAttributes())
+            {
+                var attributeName = attribute.Name.LocalName;
+                string mappedName;
+                if (AttributeNameMapper.TryGetValue(attributeName, out mappedName))
+                {
+                    writer.WriteAttributeString(
+                        null,
+                        mappedName,
+                        attribute.Name.NamespaceName,
+                        attribute.Value
+                    );
+                }
+                else
+                {
+                    writer.WriteAttributeString(
+                        null,
+                        attributeName,
+                        attribute.Name.NamespaceName,
+                        attribute.Value
+                    );
+                }
+            }
+
+            foreach (var option in Options)
+            {
+                if (option.Key.StartsWith("xml:"))
+                {
+                    writer.WriteAttributeString(
+                        null,
+                        option.Key.Substring(4),
+                        XNamespace.Xml.NamespaceName,
+                        option.Value
+                    );
+                }
+                else
+                {
+                    writer.WriteAttributeString(null, option.Key, null, option.Value);
+                }
+            }
+
+            var body = GetElementBody();
+            if (!string.IsNullOrEmpty(body))
+            {
+                writer.WriteString(body);
+            }
+            else
+            {
+                foreach (var child in Children)
+                {
+                    child.WriteContent(writer);
+                }
+            }
+
+            writer.WriteEndElement();
+        }
+
+#if !NET35
+        /// <summary>
+        /// Write TwiML to TextWriter as XML.
+        /// </summary>
+        /// <param name="textWriter">TextWriter to write XML string to.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        public Task SaveAsync(TextWriter textWriter, CancellationToken cancellationToken)
+        {
+            return SaveAsync(textWriter, SaveOptions.None, cancellationToken);
+        }
+
+        /// <summary>
+        /// Write TwiML to TextWriter as XML.
+        /// </summary>
+        /// <param name="textWriter">TextWriter to write XML string to.</param>
+        /// <param name="formattingOptions">Change generated string format.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        public async Task SaveAsync(
+            TextWriter textWriter, SaveOptions
+            formattingOptions,
+            CancellationToken cancellationToken
+        )
+        {
+            var ws = GetXmlWriterSettings(formattingOptions);
+            ws.Async = true;
+            var writer = XmlWriter.Create(textWriter, ws);
+#if NET6_0_OR_GREATER
+            await using (writer.ConfigureAwait(false))
+            {
+#else
+            using (writer)
+            {
+#endif
+                await SaveAsync(writer, cancellationToken).ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Write TwiML to Stream as XML.
+        /// </summary>
+        /// <param name="stream">Stream to write XML string to.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        public Task SaveAsync(Stream stream, CancellationToken cancellationToken)
+        {
+            return SaveAsync(stream, SaveOptions.None, cancellationToken);
+        }
+
+        /// <summary>
+        /// Write TwiML to Stream as XML.
+        /// </summary>
+        /// <param name="stream">Stream to write XML string to.</param>
+        /// <param name="formattingOptions">Change generated string format.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        public async Task SaveAsync(Stream stream, SaveOptions formattingOptions, CancellationToken cancellationToken)
+        {
+            var ws = GetXmlWriterSettings(formattingOptions);
+            ws.Async = true;
+            var writer = XmlWriter.Create(stream, ws);
+#if NET6_0_OR_GREATER
+            await using (writer.ConfigureAwait(false))
+            {
+#else
+            using (writer)
+            {
+#endif
+                await SaveAsync(writer, cancellationToken).ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Write TwiML to XmlWriter as XML. Configure the XmlWriter before invoking Save.
+        /// </summary>
+        /// <param name="writer">XmlWriter to write XML string to.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        public async Task SaveAsync(XmlWriter writer, CancellationToken cancellationToken)
+        {
+            await writer.WriteStartDocumentAsync().ConfigureAwait(false);
+            await WriteXml(writer, cancellationToken).ConfigureAwait(false);
+            await writer.WriteEndDocumentAsync().ConfigureAwait(false);
+            await writer.FlushAsync().ConfigureAwait(false);
+        }
+
+        /// <summary>
+        /// Write the Element, Attributes, and inner XML of this TwiML object.
+        /// </summary>
+        /// <param name="writer">XmlWriter to write XML string to.</param>
+        /// <param name="cancellationToken">A cancellation token.</param>
+        protected virtual async Task WriteXml(XmlWriter writer, CancellationToken cancellationToken)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            await writer.WriteStartElementAsync(null, TagName, null).ConfigureAwait(false);
+
+            foreach (var attribute in GetElementAttributes())
+            {
+                var attributeName = attribute.Name.LocalName;
+                string mappedName;
+                if (AttributeNameMapper.TryGetValue(attributeName, out mappedName))
+                {
+                    await writer.WriteAttributeStringAsync(
+                        null,
+                        mappedName,
+                        attribute.Name.NamespaceName,
+                        attribute.Value
+                    ).ConfigureAwait(false);
+                }
+                else
+                {
+                    await writer.WriteAttributeStringAsync(
+                        null,
+                        attributeName,
+                        attribute.Name.NamespaceName,
+                        attribute.Value
+                    ).ConfigureAwait(false);
+                }
+            }
+
+            foreach (var option in Options)
+            {
+                if (option.Key.StartsWith("xml:"))
+                {
+                    await writer.WriteAttributeStringAsync(
+                        null,
+                        option.Key.Substring(4),
+                        XNamespace.Xml.NamespaceName,
+                        option.Value
+                    ).ConfigureAwait(false);
+                }
+                else
+                {
+                    await writer.WriteAttributeStringAsync(null, option.Key, null, option.Value)
+                        .ConfigureAwait(false);
+                }
+            }
+
+            var body = GetElementBody();
+            if (!string.IsNullOrEmpty(body))
+            {
+                await writer.WriteStringAsync(body).ConfigureAwait(false);
+            }
+            else
+            {
+                foreach (var child in Children)
+                {
+                    await child.WriteXml(writer, cancellationToken).ConfigureAwait(false);
+                }
+            }
+
+            await writer.WriteEndElementAsync().ConfigureAwait(false);
+        }
+#endif
+
+        private static XmlWriterSettings GetXmlWriterSettings(SaveOptions saveOptions)
+        {
+            XmlWriterSettings settings = new XmlWriterSettings();
+            settings.Encoding = Encoding.UTF8;
+           
+            if ((saveOptions & SaveOptions.DisableFormatting) == 0) settings.Indent = true;
+#if !NET35
+            if ((saveOptions & SaveOptions.OmitDuplicateNamespaces) != 0)
+                settings.NamespaceHandling |= NamespaceHandling.OmitDuplicates;
+#endif
+            return settings;
+        }
+
+        /// <summary>
+        /// Generate XML string from TwiML object.
+        /// </summary>
+        public override string ToString()
+        {
+            return ToString(SaveOptions.None);
+        }
+
+        /// <summary>
+        /// Generate XML string from TwiML object.
+        /// </summary>
+        /// <param name="formattingOptions">Change generated string format.</param>
+        public string ToString(SaveOptions formattingOptions)
+        {
+            using (var writer = new Utf8StringWriter())
+            {
+                Save(writer, formattingOptions);
+                return writer.ToString();
+            }
+        }
+    }
+
+    /// <summary>
+    /// StringWriter which overrides default encoding to use UTF8.
+    /// </summary>
+    public class Utf8StringWriter : StringWriter
+    {
+        public override Encoding Encoding => Encoding.UTF8;
+    }
+}
\ No newline at end of file
diff --git a/src/Twilio/TwiML/Voice/Application.cs b/src/Twilio/TwiML/Voice/Application.cs
index ef71db232..b753d499b 100644
--- a/src/Twilio/TwiML/Voice/Application.cs
+++ b/src/Twilio/TwiML/Voice/Application.cs
@@ -110,7 +110,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Url != null)
diff --git a/src/Twilio/TwiML/Voice/Client.cs b/src/Twilio/TwiML/Voice/Client.cs
index 60efc8c3f..7a4c9d0c1 100644
--- a/src/Twilio/TwiML/Voice/Client.cs
+++ b/src/Twilio/TwiML/Voice/Client.cs
@@ -95,7 +95,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Url != null)
diff --git a/src/Twilio/TwiML/Voice/Conference.cs b/src/Twilio/TwiML/Voice/Conference.cs
index 6d1d52b32..03da0284a 100644
--- a/src/Twilio/TwiML/Voice/Conference.cs
+++ b/src/Twilio/TwiML/Voice/Conference.cs
@@ -293,7 +293,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Muted != null)
diff --git a/src/Twilio/TwiML/Voice/Config.cs b/src/Twilio/TwiML/Voice/Config.cs
index 6e1ba86a0..36aab18cb 100644
--- a/src/Twilio/TwiML/Voice/Config.cs
+++ b/src/Twilio/TwiML/Voice/Config.cs
@@ -39,7 +39,7 @@ public Config(string name = null, string value = null) : base("Config")
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Name != null)
diff --git a/src/Twilio/TwiML/Voice/Connect.cs b/src/Twilio/TwiML/Voice/Connect.cs
index f2c2c6bc1..3666bfa17 100644
--- a/src/Twilio/TwiML/Voice/Connect.cs
+++ b/src/Twilio/TwiML/Voice/Connect.cs
@@ -41,7 +41,7 @@ public Connect(Uri action = null, Twilio.Http.HttpMethod method = null) : base("
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Conversation.cs b/src/Twilio/TwiML/Voice/Conversation.cs
index a3f4e8b38..e6093b493 100644
--- a/src/Twilio/TwiML/Voice/Conversation.cs
+++ b/src/Twilio/TwiML/Voice/Conversation.cs
@@ -188,7 +188,7 @@ public Conversation(string serviceInstanceSid = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.ServiceInstanceSid != null)
diff --git a/src/Twilio/TwiML/Voice/Dial.cs b/src/Twilio/TwiML/Voice/Dial.cs
index 0ed3b60a1..c1dfc05bd 100644
--- a/src/Twilio/TwiML/Voice/Dial.cs
+++ b/src/Twilio/TwiML/Voice/Dial.cs
@@ -275,7 +275,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Enqueue.cs b/src/Twilio/TwiML/Voice/Enqueue.cs
index 24d5013f3..23f9666eb 100644
--- a/src/Twilio/TwiML/Voice/Enqueue.cs
+++ b/src/Twilio/TwiML/Voice/Enqueue.cs
@@ -85,7 +85,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Gather.cs b/src/Twilio/TwiML/Voice/Gather.cs
index 60ba91ffd..e0fb797d7 100644
--- a/src/Twilio/TwiML/Voice/Gather.cs
+++ b/src/Twilio/TwiML/Voice/Gather.cs
@@ -327,7 +327,7 @@ public Gather(IEnumerable<Gather.InputEnum> input = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Input != null)
diff --git a/src/Twilio/TwiML/Voice/Number.cs b/src/Twilio/TwiML/Voice/Number.cs
index ebd433ca7..faa5a71bb 100644
--- a/src/Twilio/TwiML/Voice/Number.cs
+++ b/src/Twilio/TwiML/Voice/Number.cs
@@ -159,7 +159,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.SendDigits != null)
diff --git a/src/Twilio/TwiML/Voice/Parameter.cs b/src/Twilio/TwiML/Voice/Parameter.cs
index 4e09c9188..4d5819643 100644
--- a/src/Twilio/TwiML/Voice/Parameter.cs
+++ b/src/Twilio/TwiML/Voice/Parameter.cs
@@ -39,7 +39,7 @@ public Parameter(string name = null, string value = null) : base("Parameter")
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Name != null)
diff --git a/src/Twilio/TwiML/Voice/Pause.cs b/src/Twilio/TwiML/Voice/Pause.cs
index b48553de1..935a1c9b4 100644
--- a/src/Twilio/TwiML/Voice/Pause.cs
+++ b/src/Twilio/TwiML/Voice/Pause.cs
@@ -33,7 +33,7 @@ public Pause(int? length = null) : base("Pause")
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Length != null)
diff --git a/src/Twilio/TwiML/Voice/Pay.cs b/src/Twilio/TwiML/Voice/Pay.cs
index 7401a5e11..e9f37e370 100644
--- a/src/Twilio/TwiML/Voice/Pay.cs
+++ b/src/Twilio/TwiML/Voice/Pay.cs
@@ -270,7 +270,7 @@ public Pay(Pay.InputEnum input = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Input != null)
diff --git a/src/Twilio/TwiML/Voice/Play.cs b/src/Twilio/TwiML/Voice/Play.cs
index 6e9cefb47..d42197170 100644
--- a/src/Twilio/TwiML/Voice/Play.cs
+++ b/src/Twilio/TwiML/Voice/Play.cs
@@ -55,7 +55,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Loop != null)
diff --git a/src/Twilio/TwiML/Voice/Prompt.cs b/src/Twilio/TwiML/Voice/Prompt.cs
index 4bf5e3b89..3c82bd823 100644
--- a/src/Twilio/TwiML/Voice/Prompt.cs
+++ b/src/Twilio/TwiML/Voice/Prompt.cs
@@ -122,7 +122,7 @@ public Prompt(Prompt.ForEnum for_ = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.For_ != null)
diff --git a/src/Twilio/TwiML/Voice/Queue.cs b/src/Twilio/TwiML/Voice/Queue.cs
index 1330fc0cd..f91d816a0 100644
--- a/src/Twilio/TwiML/Voice/Queue.cs
+++ b/src/Twilio/TwiML/Voice/Queue.cs
@@ -71,7 +71,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Url != null)
diff --git a/src/Twilio/TwiML/Voice/Record.cs b/src/Twilio/TwiML/Voice/Record.cs
index 20eafd12d..a9fe79948 100644
--- a/src/Twilio/TwiML/Voice/Record.cs
+++ b/src/Twilio/TwiML/Voice/Record.cs
@@ -141,7 +141,7 @@ public Record(Uri action = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Redirect.cs b/src/Twilio/TwiML/Voice/Redirect.cs
index d5fb144a6..a6006387b 100644
--- a/src/Twilio/TwiML/Voice/Redirect.cs
+++ b/src/Twilio/TwiML/Voice/Redirect.cs
@@ -49,7 +49,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Method != null)
diff --git a/src/Twilio/TwiML/Voice/Refer.cs b/src/Twilio/TwiML/Voice/Refer.cs
index 5a708d763..dd36b86ef 100644
--- a/src/Twilio/TwiML/Voice/Refer.cs
+++ b/src/Twilio/TwiML/Voice/Refer.cs
@@ -41,7 +41,7 @@ public Refer(Uri action = null, Twilio.Http.HttpMethod method = null) : base("Re
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Reject.cs b/src/Twilio/TwiML/Voice/Reject.cs
index 52140d649..56de60c15 100644
--- a/src/Twilio/TwiML/Voice/Reject.cs
+++ b/src/Twilio/TwiML/Voice/Reject.cs
@@ -47,7 +47,7 @@ public Reject(Reject.ReasonEnum reason = null) : base("Reject")
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Reason != null)
diff --git a/src/Twilio/TwiML/Voice/Room.cs b/src/Twilio/TwiML/Voice/Room.cs
index 41da43f7b..2dc215b0e 100644
--- a/src/Twilio/TwiML/Voice/Room.cs
+++ b/src/Twilio/TwiML/Voice/Room.cs
@@ -47,7 +47,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.ParticipantIdentity != null)
diff --git a/src/Twilio/TwiML/Voice/Say.cs b/src/Twilio/TwiML/Voice/Say.cs
index e10f28547..58c987523 100644
--- a/src/Twilio/TwiML/Voice/Say.cs
+++ b/src/Twilio/TwiML/Voice/Say.cs
@@ -236,7 +236,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Voice != null)
diff --git a/src/Twilio/TwiML/Voice/Sip.cs b/src/Twilio/TwiML/Voice/Sip.cs
index 1db062cd0..1df94c806 100644
--- a/src/Twilio/TwiML/Voice/Sip.cs
+++ b/src/Twilio/TwiML/Voice/Sip.cs
@@ -159,7 +159,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Username != null)
diff --git a/src/Twilio/TwiML/Voice/Siprec.cs b/src/Twilio/TwiML/Voice/Siprec.cs
index 8d761df76..fb17bed58 100644
--- a/src/Twilio/TwiML/Voice/Siprec.cs
+++ b/src/Twilio/TwiML/Voice/Siprec.cs
@@ -60,7 +60,7 @@ public Siprec(string name = null, string connectorName = null, Siprec.TrackEnum
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Name != null)
diff --git a/src/Twilio/TwiML/Voice/Sms.cs b/src/Twilio/TwiML/Voice/Sms.cs
index f72235ae0..bd43c2b7d 100644
--- a/src/Twilio/TwiML/Voice/Sms.cs
+++ b/src/Twilio/TwiML/Voice/Sms.cs
@@ -78,7 +78,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.To != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlBreak.cs b/src/Twilio/TwiML/Voice/SsmlBreak.cs
index 756e5ee13..05c99bc51 100644
--- a/src/Twilio/TwiML/Voice/SsmlBreak.cs
+++ b/src/Twilio/TwiML/Voice/SsmlBreak.cs
@@ -58,7 +58,7 @@ public SsmlBreak(SsmlBreak.StrengthEnum strength = null, string time = null) : b
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Strength != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlEmphasis.cs b/src/Twilio/TwiML/Voice/SsmlEmphasis.cs
index 9a86d161d..fd2f7305f 100644
--- a/src/Twilio/TwiML/Voice/SsmlEmphasis.cs
+++ b/src/Twilio/TwiML/Voice/SsmlEmphasis.cs
@@ -62,7 +62,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Level != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlLang.cs b/src/Twilio/TwiML/Voice/SsmlLang.cs
index aa7068030..23f879c35 100644
--- a/src/Twilio/TwiML/Voice/SsmlLang.cs
+++ b/src/Twilio/TwiML/Voice/SsmlLang.cs
@@ -95,7 +95,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.XmlLang != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlPhoneme.cs b/src/Twilio/TwiML/Voice/SsmlPhoneme.cs
index 29a692199..a7e601613 100644
--- a/src/Twilio/TwiML/Voice/SsmlPhoneme.cs
+++ b/src/Twilio/TwiML/Voice/SsmlPhoneme.cs
@@ -71,7 +71,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Alphabet != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlProsody.cs b/src/Twilio/TwiML/Voice/SsmlProsody.cs
index e9bd17b96..9d73ab5c2 100644
--- a/src/Twilio/TwiML/Voice/SsmlProsody.cs
+++ b/src/Twilio/TwiML/Voice/SsmlProsody.cs
@@ -64,7 +64,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Volume != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlSayAs.cs b/src/Twilio/TwiML/Voice/SsmlSayAs.cs
index 753c59dc6..2ca1a87b1 100644
--- a/src/Twilio/TwiML/Voice/SsmlSayAs.cs
+++ b/src/Twilio/TwiML/Voice/SsmlSayAs.cs
@@ -102,7 +102,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.InterpretAs != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlSub.cs b/src/Twilio/TwiML/Voice/SsmlSub.cs
index c71dc29e0..c1418cf66 100644
--- a/src/Twilio/TwiML/Voice/SsmlSub.cs
+++ b/src/Twilio/TwiML/Voice/SsmlSub.cs
@@ -48,7 +48,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Alias != null)
diff --git a/src/Twilio/TwiML/Voice/SsmlW.cs b/src/Twilio/TwiML/Voice/SsmlW.cs
index 8fe0ff50c..4563ab3aa 100644
--- a/src/Twilio/TwiML/Voice/SsmlW.cs
+++ b/src/Twilio/TwiML/Voice/SsmlW.cs
@@ -48,7 +48,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Role != null)
diff --git a/src/Twilio/TwiML/Voice/Start.cs b/src/Twilio/TwiML/Voice/Start.cs
index 114793d6a..d0bac2767 100644
--- a/src/Twilio/TwiML/Voice/Start.cs
+++ b/src/Twilio/TwiML/Voice/Start.cs
@@ -41,7 +41,7 @@ public Start(Uri action = null, Twilio.Http.HttpMethod method = null) : base("St
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Action != null)
diff --git a/src/Twilio/TwiML/Voice/Stream.cs b/src/Twilio/TwiML/Voice/Stream.cs
index 49d3bee8b..75c83e5e4 100644
--- a/src/Twilio/TwiML/Voice/Stream.cs
+++ b/src/Twilio/TwiML/Voice/Stream.cs
@@ -96,7 +96,7 @@ public Stream(string name = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Name != null)
diff --git a/src/Twilio/TwiML/Voice/Task.cs b/src/Twilio/TwiML/Voice/Task.cs
index 49ffeca4f..8238e85df 100644
--- a/src/Twilio/TwiML/Voice/Task.cs
+++ b/src/Twilio/TwiML/Voice/Task.cs
@@ -54,7 +54,7 @@ protected override string GetElementBody()
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.Priority != null)
diff --git a/src/Twilio/TwiML/Voice/VirtualAgent.cs b/src/Twilio/TwiML/Voice/VirtualAgent.cs
index 8b7cceb55..22c5bb807 100644
--- a/src/Twilio/TwiML/Voice/VirtualAgent.cs
+++ b/src/Twilio/TwiML/Voice/VirtualAgent.cs
@@ -61,7 +61,7 @@ public VirtualAgent(string connectorName = null,
         /// <summary>
         /// Return the attributes of the TwiML tag
         /// </summary>
-        protected override List<XAttribute> GetElementAttributes()
+        protected override IEnumerable<XAttribute> GetElementAttributes()
         {
             var attributes = new List<XAttribute>();
             if (this.ConnectorName != null)
diff --git a/src/Twilio/Twilio.csproj b/src/Twilio/Twilio.csproj
index 171834b2e..f3640ebe5 100644
--- a/src/Twilio/Twilio.csproj
+++ b/src/Twilio/Twilio.csproj
@@ -1,13 +1,13 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup Label="NuGet">
-    <TargetFrameworks>netstandard1.4;netstandard2.0;net451;net35</TargetFrameworks>
+    <TargetFrameworks>netstandard1.4;netstandard2.0;net451;net35;net60</TargetFrameworks>
     <IsPackable>true</IsPackable>
     <PackageId>Twilio</PackageId>
     <Description>Twilio REST API helper library</Description>
     <Copyright>Copyright © Twilio</Copyright>
     <AssemblyTitle>Twilio</AssemblyTitle>
     <NeutralLanguage>en-US</NeutralLanguage>
-    <VersionPrefix>6.6.1</VersionPrefix>
+    <VersionPrefix>6.2.2</VersionPrefix>
     <VersionSuffix></VersionSuffix>
     <Authors>Twilio</Authors>
     <NoWarn>$(NoWarn);CS1591</NoWarn>
@@ -38,6 +38,12 @@
     <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="6.19.0" />
     <PackageReference Include="System.Collections.Specialized" Version="4.3.0" />
   </ItemGroup>
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net60' ">
+    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="6.19.0" />
+    <PackageReference Include="Microsoft.IdentityModel.Tokens" Version="6.19.0" />
+    <PackageReference Include="System.Collections.Specialized" Version="4.3.0" />
+  </ItemGroup>
   <ItemGroup Condition=" '$(TargetFramework)' == 'net451' ">
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
     <PackageReference Include="System.IdentityModel.Tokens.Jwt" Version="5.1.2" />
diff --git a/test/Twilio.Test/TwiML/ApplicationSidTest.cs b/test/Twilio.Test/TwiML/ApplicationSidTest.cs
index 19b12301a..a8b0e01dd 100644
--- a/test/Twilio.Test/TwiML/ApplicationSidTest.cs
+++ b/test/Twilio.Test/TwiML/ApplicationSidTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<ApplicationSid></ApplicationSid>",
+                "<ApplicationSid />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new ApplicationSid();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<ApplicationSid newParam1=\"value\" newParam2=\"1\"></ApplicationSid>",
+                "<ApplicationSid newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ApplicationTest.cs b/test/Twilio.Test/TwiML/ApplicationTest.cs
index ae040bf17..f9d2c85f8 100644
--- a/test/Twilio.Test/TwiML/ApplicationTest.cs
+++ b/test/Twilio.Test/TwiML/ApplicationTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Application></Application>",
+                "<Application />",
                 elem.ToString()
             );
         }
@@ -52,10 +52,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Application();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Application newParam1=\"value\" newParam2=\"1\"></Application>",
+                "<Application newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -73,7 +74,7 @@ public void TestElementWithChildren()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Application>" + Environment.NewLine +
                 "  <ApplicationSid>sid</ApplicationSid>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Application>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/AutopilotTest.cs b/test/Twilio.Test/TwiML/AutopilotTest.cs
index c4f6ffe97..2b19858e6 100644
--- a/test/Twilio.Test/TwiML/AutopilotTest.cs
+++ b/test/Twilio.Test/TwiML/AutopilotTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Autopilot></Autopilot>",
+                "<Autopilot />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Autopilot();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Autopilot newParam1=\"value\" newParam2=\"1\"></Autopilot>",
+                "<Autopilot newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/BodyTest.cs b/test/Twilio.Test/TwiML/BodyTest.cs
index 9bd1cd250..72c6480cb 100644
--- a/test/Twilio.Test/TwiML/BodyTest.cs
+++ b/test/Twilio.Test/TwiML/BodyTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Body></Body>",
+                "<Body />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Body();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Body newParam1=\"value\" newParam2=\"1\"></Body>",
+                "<Body newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ClientTest.cs b/test/Twilio.Test/TwiML/ClientTest.cs
index b87759724..e95318edc 100644
--- a/test/Twilio.Test/TwiML/ClientTest.cs
+++ b/test/Twilio.Test/TwiML/ClientTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Client></Client>",
+                "<Client />",
                 elem.ToString()
             );
         }
@@ -50,10 +50,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Client();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Client newParam1=\"value\" newParam2=\"1\"></Client>",
+                "<Client newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -71,7 +72,7 @@ public void TestElementWithChildren()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Client>" + Environment.NewLine +
                 "  <Identity>client_identity</Identity>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Client>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/ConferenceTest.cs b/test/Twilio.Test/TwiML/ConferenceTest.cs
index 330e16c68..9fbc9337f 100644
--- a/test/Twilio.Test/TwiML/ConferenceTest.cs
+++ b/test/Twilio.Test/TwiML/ConferenceTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Conference></Conference>",
+                "<Conference />",
                 elem.ToString()
             );
         }
@@ -65,10 +65,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Conference();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Conference newParam1=\"value\" newParam2=\"1\"></Conference>",
+                "<Conference newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ConfigTest.cs b/test/Twilio.Test/TwiML/ConfigTest.cs
index d73797b6c..4d9a8613a 100644
--- a/test/Twilio.Test/TwiML/ConfigTest.cs
+++ b/test/Twilio.Test/TwiML/ConfigTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Config></Config>",
+                "<Config />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Config("name", "value");
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Config name=\"name\" value=\"value\"></Config>",
+                "<Config name=\"name\" value=\"value\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Config();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Config newParam1=\"value\" newParam2=\"1\"></Config>",
+                "<Config newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ConnectTest.cs b/test/Twilio.Test/TwiML/ConnectTest.cs
index 8d400acbb..e53fbc209 100644
--- a/test/Twilio.Test/TwiML/ConnectTest.cs
+++ b/test/Twilio.Test/TwiML/ConnectTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Connect></Connect>",
+                "<Connect />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Connect(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Connect action=\"https://example.com\" method=\"GET\"></Connect>",
+                "<Connect action=\"https://example.com\" method=\"GET\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Connect();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Connect newParam1=\"value\" newParam2=\"1\"></Connect>",
+                "<Connect newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -99,9 +100,9 @@ public void TestElementWithChildren()
                 "<Connect>" + Environment.NewLine +
                 "  <Room participantIdentity=\"participant_identity\">name</Room>" + Environment.NewLine +
                 "  <Autopilot>name</Autopilot>" + Environment.NewLine +
-                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></Stream>" + Environment.NewLine +
-                "  <VirtualAgent connectorName=\"connector_name\" language=\"language\" sentimentAnalysis=\"true\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></VirtualAgent>" + Environment.NewLine +
-                "  <Conversation serviceInstanceSid=\"service_instance_sid\" inboundAutocreation=\"true\" routingAssignmentTimeout=\"1\" inboundTimeout=\"1\" url=\"https://example.com\" method=\"GET\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" statusCallbackEvent=\"call-initiated\"></Conversation>" + Environment.NewLine +
+                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />" + Environment.NewLine +
+                "  <VirtualAgent connectorName=\"connector_name\" language=\"language\" sentimentAnalysis=\"true\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />" + Environment.NewLine +
+                "  <Conversation serviceInstanceSid=\"service_instance_sid\" inboundAutocreation=\"true\" routingAssignmentTimeout=\"1\" inboundTimeout=\"1\" url=\"https://example.com\" method=\"GET\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" statusCallbackEvent=\"call-initiated\" />" + Environment.NewLine +
                 "</Connect>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/ConversationTest.cs b/test/Twilio.Test/TwiML/ConversationTest.cs
index 6225f4543..58e399997 100644
--- a/test/Twilio.Test/TwiML/ConversationTest.cs
+++ b/test/Twilio.Test/TwiML/ConversationTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Conversation></Conversation>",
+                "<Conversation />",
                 elem.ToString()
             );
         }
@@ -47,7 +47,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Conversation serviceInstanceSid=\"service_instance_sid\" inboundAutocreation=\"true\" routingAssignmentTimeout=\"1\" inboundTimeout=\"1\" url=\"https://example.com\" method=\"GET\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" statusCallbackEvent=\"call-initiated\"></Conversation>",
+                "<Conversation serviceInstanceSid=\"service_instance_sid\" inboundAutocreation=\"true\" routingAssignmentTimeout=\"1\" inboundTimeout=\"1\" url=\"https://example.com\" method=\"GET\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" statusCallbackEvent=\"call-initiated\" />",
                 elem.ToString()
             );
         }
@@ -58,10 +58,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Conversation();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Conversation newParam1=\"value\" newParam2=\"1\"></Conversation>",
+                "<Conversation newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/DialTest.cs b/test/Twilio.Test/TwiML/DialTest.cs
index 31d91139e..962cc6be8 100644
--- a/test/Twilio.Test/TwiML/DialTest.cs
+++ b/test/Twilio.Test/TwiML/DialTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Dial></Dial>",
+                "<Dial />",
                 elem.ToString()
             );
         }
@@ -62,10 +62,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Dial();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Dial newParam1=\"value\" newParam2=\"1\"></Dial>",
+                "<Dial newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -81,7 +82,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Dial>" + Environment.NewLine +
                 "  <Client>" + Environment.NewLine +
-                "    <Identity></Identity>" + Environment.NewLine +
+                "    <Identity />" + Environment.NewLine +
                 "  </Client>" + Environment.NewLine +
                 "</Dial>",
                 elem.ToString()
diff --git a/test/Twilio.Test/TwiML/EchoTest.cs b/test/Twilio.Test/TwiML/EchoTest.cs
index 0a59e60e4..c88f8b31f 100644
--- a/test/Twilio.Test/TwiML/EchoTest.cs
+++ b/test/Twilio.Test/TwiML/EchoTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Echo></Echo>",
+                "<Echo />",
                 elem.ToString()
             );
         }
@@ -32,10 +32,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Echo();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Echo newParam1=\"value\" newParam2=\"1\"></Echo>",
+                "<Echo newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/EnqueueTest.cs b/test/Twilio.Test/TwiML/EnqueueTest.cs
index 7b3ed5b78..6a1858585 100644
--- a/test/Twilio.Test/TwiML/EnqueueTest.cs
+++ b/test/Twilio.Test/TwiML/EnqueueTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Enqueue></Enqueue>",
+                "<Enqueue />",
                 elem.ToString()
             );
         }
@@ -51,10 +51,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Enqueue();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Enqueue newParam1=\"value\" newParam2=\"1\"></Enqueue>",
+                "<Enqueue newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/FaxResponseTest.cs b/test/Twilio.Test/TwiML/FaxResponseTest.cs
index 61df4aa5f..553ec50b6 100644
--- a/test/Twilio.Test/TwiML/FaxResponseTest.cs
+++ b/test/Twilio.Test/TwiML/FaxResponseTest.cs
@@ -22,7 +22,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response></Response>",
+                "<Response />",
                 elem.ToString()
             );
         }
@@ -33,10 +33,11 @@ public void TestElementWithExtraAttributes()
             var elem = new FaxResponse();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response newParam1=\"value\" newParam2=\"1\"></Response>",
+                "<Response newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -57,7 +58,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Response>" + Environment.NewLine +
-                "  <Receive action=\"https://example.com\" method=\"GET\" mediaType=\"application/pdf\" pageSize=\"letter\" storeMedia=\"true\"></Receive>" + Environment.NewLine +
+                "  <Receive action=\"https://example.com\" method=\"GET\" mediaType=\"application/pdf\" pageSize=\"letter\" storeMedia=\"true\" />" + Environment.NewLine +
                 "</Response>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/GatherTest.cs b/test/Twilio.Test/TwiML/GatherTest.cs
index 5eb842a5e..f728f1dc0 100644
--- a/test/Twilio.Test/TwiML/GatherTest.cs
+++ b/test/Twilio.Test/TwiML/GatherTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Gather></Gather>",
+                "<Gather />",
                 elem.ToString()
             );
         }
@@ -51,7 +51,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Gather input=\"dtmf\" action=\"https://example.com\" method=\"GET\" timeout=\"1\" speechTimeout=\"speech_timeout\" maxSpeechTime=\"1\" profanityFilter=\"true\" finishOnKey=\"finish_on_key\" numDigits=\"1\" partialResultCallback=\"https://example.com\" partialResultCallbackMethod=\"GET\" language=\"af-ZA\" hints=\"hints\" bargeIn=\"true\" debug=\"true\" actionOnEmptyResult=\"true\" speechModel=\"default\" enhanced=\"true\"></Gather>",
+                "<Gather input=\"dtmf\" action=\"https://example.com\" method=\"GET\" timeout=\"1\" speechTimeout=\"speech_timeout\" maxSpeechTime=\"1\" profanityFilter=\"true\" finishOnKey=\"finish_on_key\" numDigits=\"1\" partialResultCallback=\"https://example.com\" partialResultCallbackMethod=\"GET\" language=\"af-ZA\" hints=\"hints\" bargeIn=\"true\" debug=\"true\" actionOnEmptyResult=\"true\" speechModel=\"default\" enhanced=\"true\" />",
                 elem.ToString()
             );
         }
@@ -62,10 +62,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Gather();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Gather newParam1=\"value\" newParam2=\"1\"></Gather>",
+                "<Gather newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -81,7 +82,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Gather>" + Environment.NewLine +
                 "  <Say>" + Environment.NewLine +
-                "    <break></break>" + Environment.NewLine +
+                "    <break />" + Environment.NewLine +
                 "  </Say>" + Environment.NewLine +
                 "</Gather>",
                 elem.ToString()
@@ -103,7 +104,7 @@ public void TestElementWithChildren()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Gather>" + Environment.NewLine +
                 "  <Say voice=\"man\" loop=\"1\" language=\"arb\">message</Say>" + Environment.NewLine +
-                "  <Pause length=\"1\"></Pause>" + Environment.NewLine +
+                "  <Pause length=\"1\" />" + Environment.NewLine +
                 "  <Play loop=\"1\" digits=\"digits\">https://example.com</Play>" + Environment.NewLine +
                 "</Gather>",
                 elem.ToString()
diff --git a/test/Twilio.Test/TwiML/HangupTest.cs b/test/Twilio.Test/TwiML/HangupTest.cs
index 20aa9bead..1e572fa47 100644
--- a/test/Twilio.Test/TwiML/HangupTest.cs
+++ b/test/Twilio.Test/TwiML/HangupTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Hangup></Hangup>",
+                "<Hangup />",
                 elem.ToString()
             );
         }
@@ -32,10 +32,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Hangup();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Hangup newParam1=\"value\" newParam2=\"1\"></Hangup>",
+                "<Hangup newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -50,7 +51,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Hangup>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Hangup>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/IdentityTest.cs b/test/Twilio.Test/TwiML/IdentityTest.cs
index 9051dcaab..6b036ca3e 100644
--- a/test/Twilio.Test/TwiML/IdentityTest.cs
+++ b/test/Twilio.Test/TwiML/IdentityTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Identity></Identity>",
+                "<Identity />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Identity();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Identity newParam1=\"value\" newParam2=\"1\"></Identity>",
+                "<Identity newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/LeaveTest.cs b/test/Twilio.Test/TwiML/LeaveTest.cs
index 5cb620488..f68d76d2f 100644
--- a/test/Twilio.Test/TwiML/LeaveTest.cs
+++ b/test/Twilio.Test/TwiML/LeaveTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Leave></Leave>",
+                "<Leave />",
                 elem.ToString()
             );
         }
@@ -32,10 +32,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Leave();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Leave newParam1=\"value\" newParam2=\"1\"></Leave>",
+                "<Leave newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/MediaTest.cs b/test/Twilio.Test/TwiML/MediaTest.cs
index 29a979b6e..2e461b051 100644
--- a/test/Twilio.Test/TwiML/MediaTest.cs
+++ b/test/Twilio.Test/TwiML/MediaTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Media></Media>",
+                "<Media />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Media();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Media newParam1=\"value\" newParam2=\"1\"></Media>",
+                "<Media newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/MessageTest.cs b/test/Twilio.Test/TwiML/MessageTest.cs
index 3a299fe8c..d7c619cdb 100644
--- a/test/Twilio.Test/TwiML/MessageTest.cs
+++ b/test/Twilio.Test/TwiML/MessageTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Message></Message>",
+                "<Message />",
                 elem.ToString()
             );
         }
@@ -50,10 +50,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Message();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Message newParam1=\"value\" newParam2=\"1\"></Message>",
+                "<Message newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/MessagingResponseTest.cs b/test/Twilio.Test/TwiML/MessagingResponseTest.cs
index 49fd79c47..b7abe7182 100644
--- a/test/Twilio.Test/TwiML/MessagingResponseTest.cs
+++ b/test/Twilio.Test/TwiML/MessagingResponseTest.cs
@@ -22,7 +22,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response></Response>",
+                "<Response />",
                 elem.ToString()
             );
         }
@@ -33,10 +33,11 @@ public void TestElementWithExtraAttributes()
             var elem = new MessagingResponse();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response newParam1=\"value\" newParam2=\"1\"></Response>",
+                "<Response newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -52,7 +53,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Response>" + Environment.NewLine +
                 "  <Message>" + Environment.NewLine +
-                "    <Body></Body>" + Environment.NewLine +
+                "    <Body />" + Environment.NewLine +
                 "  </Message>" + Environment.NewLine +
                 "</Response>",
                 elem.ToString()
diff --git a/test/Twilio.Test/TwiML/NumberTest.cs b/test/Twilio.Test/TwiML/NumberTest.cs
index b5524cce9..1ac86c254 100644
--- a/test/Twilio.Test/TwiML/NumberTest.cs
+++ b/test/Twilio.Test/TwiML/NumberTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Number></Number>",
+                "<Number />",
                 elem.ToString()
             );
         }
@@ -59,10 +59,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Number();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Number newParam1=\"value\" newParam2=\"1\"></Number>",
+                "<Number newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ParameterTest.cs b/test/Twilio.Test/TwiML/ParameterTest.cs
index a5c337068..108772ce3 100644
--- a/test/Twilio.Test/TwiML/ParameterTest.cs
+++ b/test/Twilio.Test/TwiML/ParameterTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Parameter></Parameter>",
+                "<Parameter />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Parameter("name", "value");
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Parameter name=\"name\" value=\"value\"></Parameter>",
+                "<Parameter name=\"name\" value=\"value\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Parameter();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Parameter newParam1=\"value\" newParam2=\"1\"></Parameter>",
+                "<Parameter newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/PauseTest.cs b/test/Twilio.Test/TwiML/PauseTest.cs
index 1b9505e3a..53761439d 100644
--- a/test/Twilio.Test/TwiML/PauseTest.cs
+++ b/test/Twilio.Test/TwiML/PauseTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pause></Pause>",
+                "<Pause />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Pause(1);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pause length=\"1\"></Pause>",
+                "<Pause length=\"1\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Pause();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pause newParam1=\"value\" newParam2=\"1\"></Pause>",
+                "<Pause newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/PayTest.cs b/test/Twilio.Test/TwiML/PayTest.cs
index 1a7d60982..affdbefde 100644
--- a/test/Twilio.Test/TwiML/PayTest.cs
+++ b/test/Twilio.Test/TwiML/PayTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pay></Pay>",
+                "<Pay />",
                 elem.ToString()
             );
         }
@@ -51,7 +51,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pay input=\"dtmf\" action=\"https://example.com\" bankAccountType=\"consumer-checking\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" timeout=\"1\" maxAttempts=\"1\" securityCode=\"true\" postalCode=\"postal_code\" minPostalCodeLength=\"1\" paymentConnector=\"payment_connector\" paymentMethod=\"ach-debit\" tokenType=\"one-time\" chargeAmount=\"charge_amount\" currency=\"currency\" description=\"description\" validCardTypes=\"visa\" language=\"de-DE\"></Pay>",
+                "<Pay input=\"dtmf\" action=\"https://example.com\" bankAccountType=\"consumer-checking\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" timeout=\"1\" maxAttempts=\"1\" securityCode=\"true\" postalCode=\"postal_code\" minPostalCodeLength=\"1\" paymentConnector=\"payment_connector\" paymentMethod=\"ach-debit\" tokenType=\"one-time\" chargeAmount=\"charge_amount\" currency=\"currency\" description=\"description\" validCardTypes=\"visa\" language=\"de-DE\" />",
                 elem.ToString()
             );
         }
@@ -62,10 +62,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Pay();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Pay newParam1=\"value\" newParam2=\"1\"></Pay>",
+                "<Pay newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -81,7 +82,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Pay>" + Environment.NewLine +
                 "  <Prompt>" + Environment.NewLine +
-                "    <Say></Say>" + Environment.NewLine +
+                "    <Say />" + Environment.NewLine +
                 "  </Prompt>" + Environment.NewLine +
                 "</Pay>",
                 elem.ToString()
@@ -106,8 +107,8 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Pay>" + Environment.NewLine +
-                "  <Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\"></Prompt>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\" />" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Pay>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/PlayTest.cs b/test/Twilio.Test/TwiML/PlayTest.cs
index e89ac63f0..2051fe6f6 100644
--- a/test/Twilio.Test/TwiML/PlayTest.cs
+++ b/test/Twilio.Test/TwiML/PlayTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Play></Play>",
+                "<Play />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Play();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Play newParam1=\"value\" newParam2=\"1\"></Play>",
+                "<Play newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/PromptTest.cs b/test/Twilio.Test/TwiML/PromptTest.cs
index b9d65df0e..368cf134f 100644
--- a/test/Twilio.Test/TwiML/PromptTest.cs
+++ b/test/Twilio.Test/TwiML/PromptTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Prompt></Prompt>",
+                "<Prompt />",
                 elem.ToString()
             );
         }
@@ -38,7 +38,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\"></Prompt>",
+                "<Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\" />",
                 elem.ToString()
             );
         }
@@ -49,10 +49,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Prompt();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Prompt newParam1=\"value\" newParam2=\"1\"></Prompt>",
+                "<Prompt newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -68,7 +69,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Prompt>" + Environment.NewLine +
                 "  <Say>" + Environment.NewLine +
-                "    <break></break>" + Environment.NewLine +
+                "    <break />" + Environment.NewLine +
                 "  </Say>" + Environment.NewLine +
                 "</Prompt>",
                 elem.ToString()
@@ -91,7 +92,7 @@ public void TestElementWithChildren()
                 "<Prompt>" + Environment.NewLine +
                 "  <Say voice=\"man\" loop=\"1\" language=\"arb\">message</Say>" + Environment.NewLine +
                 "  <Play loop=\"1\" digits=\"digits\">https://example.com</Play>" + Environment.NewLine +
-                "  <Pause length=\"1\"></Pause>" + Environment.NewLine +
+                "  <Pause length=\"1\" />" + Environment.NewLine +
                 "</Prompt>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/QueueTest.cs b/test/Twilio.Test/TwiML/QueueTest.cs
index b7714b0e9..8394499a6 100644
--- a/test/Twilio.Test/TwiML/QueueTest.cs
+++ b/test/Twilio.Test/TwiML/QueueTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Queue></Queue>",
+                "<Queue />",
                 elem.ToString()
             );
         }
@@ -49,10 +49,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Queue();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Queue newParam1=\"value\" newParam2=\"1\"></Queue>",
+                "<Queue newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ReceiveTest.cs b/test/Twilio.Test/TwiML/ReceiveTest.cs
index 809b430e4..cb273972a 100644
--- a/test/Twilio.Test/TwiML/ReceiveTest.cs
+++ b/test/Twilio.Test/TwiML/ReceiveTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Receive></Receive>",
+                "<Receive />",
                 elem.ToString()
             );
         }
@@ -38,7 +38,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Receive action=\"https://example.com\" method=\"GET\" mediaType=\"application/pdf\" pageSize=\"letter\" storeMedia=\"true\"></Receive>",
+                "<Receive action=\"https://example.com\" method=\"GET\" mediaType=\"application/pdf\" pageSize=\"letter\" storeMedia=\"true\" />",
                 elem.ToString()
             );
         }
@@ -49,10 +49,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Receive();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Receive newParam1=\"value\" newParam2=\"1\"></Receive>",
+                "<Receive newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/RecordTest.cs b/test/Twilio.Test/TwiML/RecordTest.cs
index 587b11322..319f48274 100644
--- a/test/Twilio.Test/TwiML/RecordTest.cs
+++ b/test/Twilio.Test/TwiML/RecordTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Record></Record>",
+                "<Record />",
                 elem.ToString()
             );
         }
@@ -45,7 +45,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Record action=\"https://example.com\" method=\"GET\" timeout=\"1\" finishOnKey=\"finish_on_key\" maxLength=\"1\" playBeep=\"true\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" transcribe=\"true\" transcribeCallback=\"https://example.com\"></Record>",
+                "<Record action=\"https://example.com\" method=\"GET\" timeout=\"1\" finishOnKey=\"finish_on_key\" maxLength=\"1\" playBeep=\"true\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" transcribe=\"true\" transcribeCallback=\"https://example.com\" />",
                 elem.ToString()
             );
         }
@@ -56,10 +56,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Record();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Record newParam1=\"value\" newParam2=\"1\"></Record>",
+                "<Record newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/RedirectTest.cs b/test/Twilio.Test/TwiML/RedirectTest.cs
index 41ce20a08..d19b555d4 100644
--- a/test/Twilio.Test/TwiML/RedirectTest.cs
+++ b/test/Twilio.Test/TwiML/RedirectTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Redirect></Redirect>",
+                "<Redirect />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Redirect();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Redirect newParam1=\"value\" newParam2=\"1\"></Redirect>",
+                "<Redirect newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ReferSipTest.cs b/test/Twilio.Test/TwiML/ReferSipTest.cs
index 800dc67a6..988ca399f 100644
--- a/test/Twilio.Test/TwiML/ReferSipTest.cs
+++ b/test/Twilio.Test/TwiML/ReferSipTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sip></Sip>",
+                "<Sip />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new ReferSip();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sip newParam1=\"value\" newParam2=\"1\"></Sip>",
+                "<Sip newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/ReferTest.cs b/test/Twilio.Test/TwiML/ReferTest.cs
index dfe6b9746..faff70453 100644
--- a/test/Twilio.Test/TwiML/ReferTest.cs
+++ b/test/Twilio.Test/TwiML/ReferTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Refer></Refer>",
+                "<Refer />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Refer(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Refer action=\"https://example.com\" method=\"GET\"></Refer>",
+                "<Refer action=\"https://example.com\" method=\"GET\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Refer();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Refer newParam1=\"value\" newParam2=\"1\"></Refer>",
+                "<Refer newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/RejectTest.cs b/test/Twilio.Test/TwiML/RejectTest.cs
index 91ac2f0ee..fad737b35 100644
--- a/test/Twilio.Test/TwiML/RejectTest.cs
+++ b/test/Twilio.Test/TwiML/RejectTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Reject></Reject>",
+                "<Reject />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Reject(Reject.ReasonEnum.Rejected);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Reject reason=\"rejected\"></Reject>",
+                "<Reject reason=\"rejected\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Reject();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Reject newParam1=\"value\" newParam2=\"1\"></Reject>",
+                "<Reject newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -61,7 +62,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Reject>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Reject>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/RoomTest.cs b/test/Twilio.Test/TwiML/RoomTest.cs
index cb72a684b..60a6a6006 100644
--- a/test/Twilio.Test/TwiML/RoomTest.cs
+++ b/test/Twilio.Test/TwiML/RoomTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Room></Room>",
+                "<Room />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Room();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Room newParam1=\"value\" newParam2=\"1\"></Room>",
+                "<Room newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SayTest.cs b/test/Twilio.Test/TwiML/SayTest.cs
index 91f67bd41..78a39be35 100644
--- a/test/Twilio.Test/TwiML/SayTest.cs
+++ b/test/Twilio.Test/TwiML/SayTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Say></Say>",
+                "<Say />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Say();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Say newParam1=\"value\" newParam2=\"1\"></Say>",
+                "<Say newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -79,7 +80,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Say>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <p>words</p>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SerializationTest.cs b/test/Twilio.Test/TwiML/SerializationTest.cs
new file mode 100644
index 000000000..811837592
--- /dev/null
+++ b/test/Twilio.Test/TwiML/SerializationTest.cs
@@ -0,0 +1,256 @@
+using NUnit.Framework;
+using System;
+using System.IO;
+using System.Threading;
+using System.Xml.Linq;
+using Twilio.Converters;
+using Twilio.TwiML;
+using Twilio.TwiML.Voice;
+
+namespace Twilio.Tests.TwiML
+{
+    [TestFixture]
+    public class SerializationTest : TwilioTest
+    {
+        private Twilio.TwiML.TwiML twiml;
+        private string twimlOutput;
+
+        public SerializationTest()
+        {
+            var elem = new VoiceResponse();
+
+            elem.Connect(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
+
+            elem.Dial(
+                "number",
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                1,
+                true,
+                1,
+                "caller_id",
+                Dial.RecordEnum.DoNotRecord,
+                Dial.TrimEnum.TrimSilence,
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                Promoter.ListOfOne(Dial.RecordingEventEnum.InProgress),
+                true,
+                Dial.RingToneEnum.At,
+                Dial.RecordingTrackEnum.Both,
+                true,
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get
+            );
+
+            elem.Echo();
+
+            elem.Enqueue(
+                "name",
+                new Uri("https://example.com"),
+                1,
+                Twilio.Http.HttpMethod.Get,
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                "workflow_sid"
+            );
+
+            elem.Gather(
+                Promoter.ListOfOne(Gather.InputEnum.Dtmf),
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                1,
+                "speech_timeout",
+                1,
+                true,
+                "finish_on_key",
+                1,
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                Gather.LanguageEnum.AfZa,
+                "hints",
+                true,
+                true,
+                true,
+                Gather.SpeechModelEnum.Default,
+                true
+            );
+
+            elem.Hangup();
+
+            elem.Leave();
+
+            elem.Pause(1);
+
+            elem.Play(new Uri("https://example.com"), 1, "digits");
+
+            elem.Queue(
+                "name",
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                "reservation_sid",
+                "post_work_activity_sid"
+            );
+
+            elem.Record(
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                1,
+                "finish_on_key",
+                1,
+                true,
+                Record.TrimEnum.TrimSilence,
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                Promoter.ListOfOne(Record.RecordingEventEnum.InProgress),
+                true,
+                new Uri("https://example.com")
+            );
+
+            elem.Redirect(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
+
+            elem.Reject(Reject.ReasonEnum.Rejected);
+
+            elem.Say("message", Say.VoiceEnum.Man, 1, Say.LanguageEnum.Arb);
+
+            elem.Sms(
+                "message",
+                new Twilio.Types.PhoneNumber("+15558675310"),
+                new Twilio.Types.PhoneNumber("+15017122661"),
+                new Uri("https://example.com"),
+                Twilio.Http.HttpMethod.Get,
+                new Uri("https://example.com")
+            );
+
+            elem.Pay(
+                Pay.InputEnum.Dtmf,
+                new Uri("https://example.com"),
+                Pay.BankAccountTypeEnum.ConsumerChecking,
+                new Uri("https://example.com"),
+                Pay.StatusCallbackMethodEnum.Get,
+                1,
+                1,
+                true,
+                "postal_code",
+                1,
+                "payment_connector",
+                Pay.PaymentMethodEnum.AchDebit,
+                Pay.TokenTypeEnum.OneTime,
+                "charge_amount",
+                "currency",
+                "description",
+                Promoter.ListOfOne(Pay.ValidCardTypesEnum.Visa),
+                Pay.LanguageEnum.DeDe
+            );
+
+            elem.Prompt(
+                Prompt.ForEnum.PaymentCardNumber,
+                Promoter.ListOfOne(Prompt.ErrorTypeEnum.Timeout),
+                Promoter.ListOfOne(Prompt.CardTypeEnum.Visa),
+                Promoter.ListOfOne(1),
+                true
+            );
+
+            elem.Start(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
+
+            elem.Stop();
+
+            elem.Refer(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
+
+            twiml = elem;
+
+            twimlOutput = "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
+                          "<Response>" + Environment.NewLine +
+                          "  <Connect action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
+                          "  <Dial action=\"https://example.com\" method=\"GET\" timeout=\"1\" hangupOnStar=\"true\" timeLimit=\"1\" callerId=\"caller_id\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" answerOnBridge=\"true\" ringTone=\"at\" recordingTrack=\"both\" sequential=\"true\" referUrl=\"https://example.com\" referMethod=\"GET\">number</Dial>" +
+                          Environment.NewLine +
+                          "  <Echo />" + Environment.NewLine +
+                          "  <Enqueue action=\"https://example.com\" maxQueueSize=\"1\" method=\"GET\" waitUrl=\"https://example.com\" waitUrlMethod=\"GET\" workflowSid=\"workflow_sid\">name</Enqueue>" +
+                          Environment.NewLine +
+                          "  <Gather input=\"dtmf\" action=\"https://example.com\" method=\"GET\" timeout=\"1\" speechTimeout=\"speech_timeout\" maxSpeechTime=\"1\" profanityFilter=\"true\" finishOnKey=\"finish_on_key\" numDigits=\"1\" partialResultCallback=\"https://example.com\" partialResultCallbackMethod=\"GET\" language=\"af-ZA\" hints=\"hints\" bargeIn=\"true\" debug=\"true\" actionOnEmptyResult=\"true\" speechModel=\"default\" enhanced=\"true\" />" +
+                          Environment.NewLine +
+                          "  <Hangup />" + Environment.NewLine +
+                          "  <Leave />" + Environment.NewLine +
+                          "  <Pause length=\"1\" />" + Environment.NewLine +
+                          "  <Play loop=\"1\" digits=\"digits\">https://example.com</Play>" + Environment.NewLine +
+                          "  <Queue url=\"https://example.com\" method=\"GET\" reservationSid=\"reservation_sid\" postWorkActivitySid=\"post_work_activity_sid\">name</Queue>" +
+                          Environment.NewLine +
+                          "  <Record action=\"https://example.com\" method=\"GET\" timeout=\"1\" finishOnKey=\"finish_on_key\" maxLength=\"1\" playBeep=\"true\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" transcribe=\"true\" transcribeCallback=\"https://example.com\" />" +
+                          Environment.NewLine +
+                          "  <Redirect method=\"GET\">https://example.com</Redirect>" + Environment.NewLine +
+                          "  <Reject reason=\"rejected\" />" + Environment.NewLine +
+                          "  <Say voice=\"man\" loop=\"1\" language=\"arb\">message</Say>" + Environment.NewLine +
+                          "  <Sms to=\"+15558675310\" from=\"+15017122661\" action=\"https://example.com\" method=\"GET\" statusCallback=\"https://example.com\">message</Sms>" +
+                          Environment.NewLine +
+                          "  <Pay input=\"dtmf\" action=\"https://example.com\" bankAccountType=\"consumer-checking\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" timeout=\"1\" maxAttempts=\"1\" securityCode=\"true\" postalCode=\"postal_code\" minPostalCodeLength=\"1\" paymentConnector=\"payment_connector\" paymentMethod=\"ach-debit\" tokenType=\"one-time\" chargeAmount=\"charge_amount\" currency=\"currency\" description=\"description\" validCardTypes=\"visa\" language=\"de-DE\" />" +
+                          Environment.NewLine +
+                          "  <Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\" />" +
+                          Environment.NewLine +
+                          "  <Start action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
+                          "  <Stop />" + Environment.NewLine +
+                          "  <Refer action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
+                          "</Response>";
+        }
+
+        [Test]
+        public void TestSaveStream()
+        {
+            string output;
+            using (var memoryStream = new MemoryStream())
+            {
+                twiml.Save(memoryStream);
+                memoryStream.Seek(0, SeekOrigin.Begin);
+                using (var reader = new StreamReader(memoryStream))
+                {
+                    output = reader.ReadToEnd();
+                }
+            }
+
+            Assert.AreEqual(twimlOutput, output);
+        }
+
+        [Test]
+        public void TestSaveTextWriter()
+        {
+            string output;
+            using (var writer = new Utf8StringWriter())
+            {
+                twiml.Save(writer);
+                output = writer.ToString();
+            }
+
+            Assert.AreEqual(twimlOutput, output);
+        }
+
+#if !NET35
+        [Test]
+        public async System.Threading.Tasks.Task TestSaveAsyncStream()
+        {
+            string output;
+            using (var memoryStream = new MemoryStream())
+            {
+                await twiml.SaveAsync(memoryStream, CancellationToken.None);
+                memoryStream.Seek(0, SeekOrigin.Begin);
+                using (var reader = new StreamReader(memoryStream))
+                {
+                    output = await reader.ReadToEndAsync();
+                }
+            }
+            
+            Assert.AreEqual(twimlOutput, output);
+        }
+        
+        [Test]
+        public async System.Threading.Tasks.Task TestSaveAsyncTextWriter()
+        {
+            string output;
+            using (var writer = new Utf8StringWriter())
+            {
+                await twiml.SaveAsync(writer, CancellationToken.None);
+                output = writer.ToString();
+            }
+            
+            Assert.AreEqual(twimlOutput, output);
+        }
+#endif
+    }
+}
\ No newline at end of file
diff --git a/test/Twilio.Test/TwiML/SimTest.cs b/test/Twilio.Test/TwiML/SimTest.cs
index 82ff3fa42..5db8bade9 100644
--- a/test/Twilio.Test/TwiML/SimTest.cs
+++ b/test/Twilio.Test/TwiML/SimTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sim></Sim>",
+                "<Sim />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Sim();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sim newParam1=\"value\" newParam2=\"1\"></Sim>",
+                "<Sim newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SipTest.cs b/test/Twilio.Test/TwiML/SipTest.cs
index 860ed4aad..752ab7edd 100644
--- a/test/Twilio.Test/TwiML/SipTest.cs
+++ b/test/Twilio.Test/TwiML/SipTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sip></Sip>",
+                "<Sip />",
                 elem.ToString()
             );
         }
@@ -59,10 +59,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Sip();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sip newParam1=\"value\" newParam2=\"1\"></Sip>",
+                "<Sip newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SiprecTest.cs b/test/Twilio.Test/TwiML/SiprecTest.cs
index 36a3be33d..a832229e5 100644
--- a/test/Twilio.Test/TwiML/SiprecTest.cs
+++ b/test/Twilio.Test/TwiML/SiprecTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Siprec></Siprec>",
+                "<Siprec />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Siprec("name", "connector_name", Siprec.TrackEnum.InboundTrack);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\"></Siprec>",
+                "<Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Siprec();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Siprec newParam1=\"value\" newParam2=\"1\"></Siprec>",
+                "<Siprec newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -61,7 +62,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Siprec>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Siprec>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/SmsTest.cs b/test/Twilio.Test/TwiML/SmsTest.cs
index 7737faee8..cb0a2fb3e 100644
--- a/test/Twilio.Test/TwiML/SmsTest.cs
+++ b/test/Twilio.Test/TwiML/SmsTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sms></Sms>",
+                "<Sms />",
                 elem.ToString()
             );
         }
@@ -50,10 +50,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Sms();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Sms newParam1=\"value\" newParam2=\"1\"></Sms>",
+                "<Sms newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SsmlBreakTest.cs b/test/Twilio.Test/TwiML/SsmlBreakTest.cs
index 47de34aba..1b3836acb 100644
--- a/test/Twilio.Test/TwiML/SsmlBreakTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlBreakTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<break></break>",
+                "<break />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new SsmlBreak(SsmlBreak.StrengthEnum.None, "time");
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<break strength=\"none\" time=\"time\"></break>",
+                "<break strength=\"none\" time=\"time\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlBreak();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<break newParam1=\"value\" newParam2=\"1\"></break>",
+                "<break newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SsmlEmphasisTest.cs b/test/Twilio.Test/TwiML/SsmlEmphasisTest.cs
index 68603357e..66a6a6ea5 100644
--- a/test/Twilio.Test/TwiML/SsmlEmphasisTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlEmphasisTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<emphasis></emphasis>",
+                "<emphasis />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlEmphasis();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<emphasis newParam1=\"value\" newParam2=\"1\"></emphasis>",
+                "<emphasis newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -75,7 +76,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<emphasis>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <phoneme alphabet=\"ipa\" ph=\"ph\">words</phoneme>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SsmlLangTest.cs b/test/Twilio.Test/TwiML/SsmlLangTest.cs
index bf25e8cff..41f7790cf 100644
--- a/test/Twilio.Test/TwiML/SsmlLangTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlLangTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<lang></lang>",
+                "<lang />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlLang();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<lang newParam1=\"value\" newParam2=\"1\"></lang>",
+                "<lang newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -79,7 +80,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<lang>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <p>words</p>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SsmlPTest.cs b/test/Twilio.Test/TwiML/SsmlPTest.cs
index 9534890a8..d204a21b0 100644
--- a/test/Twilio.Test/TwiML/SsmlPTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlPTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<p></p>",
+                "<p />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlP();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<p newParam1=\"value\" newParam2=\"1\"></p>",
+                "<p newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -77,7 +78,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<p>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <phoneme alphabet=\"ipa\" ph=\"ph\">words</phoneme>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SsmlPhonemeTest.cs b/test/Twilio.Test/TwiML/SsmlPhonemeTest.cs
index 2469c3299..56ae26cd6 100644
--- a/test/Twilio.Test/TwiML/SsmlPhonemeTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlPhonemeTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<phoneme></phoneme>",
+                "<phoneme />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlPhoneme();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<phoneme newParam1=\"value\" newParam2=\"1\"></phoneme>",
+                "<phoneme newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SsmlProsodyTest.cs b/test/Twilio.Test/TwiML/SsmlProsodyTest.cs
index 1693cd6d8..1be35b31c 100644
--- a/test/Twilio.Test/TwiML/SsmlProsodyTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlProsodyTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<prosody></prosody>",
+                "<prosody />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlProsody();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<prosody newParam1=\"value\" newParam2=\"1\"></prosody>",
+                "<prosody newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -79,7 +80,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<prosody>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <p>words</p>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SsmlSTest.cs b/test/Twilio.Test/TwiML/SsmlSTest.cs
index 75a385799..93b3d07c4 100644
--- a/test/Twilio.Test/TwiML/SsmlSTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlSTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<s></s>",
+                "<s />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlS();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<s newParam1=\"value\" newParam2=\"1\"></s>",
+                "<s newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -75,7 +76,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<s>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <lang xml:lang=\"arb\">words</lang>" + Environment.NewLine +
                 "  <phoneme alphabet=\"ipa\" ph=\"ph\">words</phoneme>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/SsmlSayAsTest.cs b/test/Twilio.Test/TwiML/SsmlSayAsTest.cs
index 53a5e78eb..d9c2463e9 100644
--- a/test/Twilio.Test/TwiML/SsmlSayAsTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlSayAsTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<say-as></say-as>",
+                "<say-as />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlSayAs();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<say-as newParam1=\"value\" newParam2=\"1\"></say-as>",
+                "<say-as newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SsmlSubTest.cs b/test/Twilio.Test/TwiML/SsmlSubTest.cs
index 42a04f44d..92a2a93c9 100644
--- a/test/Twilio.Test/TwiML/SsmlSubTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlSubTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<sub></sub>",
+                "<sub />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlSub();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<sub newParam1=\"value\" newParam2=\"1\"></sub>",
+                "<sub newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/SsmlWTest.cs b/test/Twilio.Test/TwiML/SsmlWTest.cs
index 52bee0a20..17d638db1 100644
--- a/test/Twilio.Test/TwiML/SsmlWTest.cs
+++ b/test/Twilio.Test/TwiML/SsmlWTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<w></w>",
+                "<w />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new SsmlW();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<w newParam1=\"value\" newParam2=\"1\"></w>",
+                "<w newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -71,7 +72,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<w>" + Environment.NewLine +
-                "  <break strength=\"none\" time=\"time\"></break>" + Environment.NewLine +
+                "  <break strength=\"none\" time=\"time\" />" + Environment.NewLine +
                 "  <emphasis level=\"strong\">words</emphasis>" + Environment.NewLine +
                 "  <phoneme alphabet=\"ipa\" ph=\"ph\">words</phoneme>" + Environment.NewLine +
                 "  <prosody volume=\"volume\" rate=\"rate\" pitch=\"pitch\">words</prosody>" + Environment.NewLine +
diff --git a/test/Twilio.Test/TwiML/StartTest.cs b/test/Twilio.Test/TwiML/StartTest.cs
index 0e6636434..34fbfd023 100644
--- a/test/Twilio.Test/TwiML/StartTest.cs
+++ b/test/Twilio.Test/TwiML/StartTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Start></Start>",
+                "<Start />",
                 elem.ToString()
             );
         }
@@ -32,7 +32,7 @@ public void TestElementWithParams()
             var elem = new Start(new Uri("https://example.com"), Twilio.Http.HttpMethod.Get);
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Start action=\"https://example.com\" method=\"GET\"></Start>",
+                "<Start action=\"https://example.com\" method=\"GET\" />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Start();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Start newParam1=\"value\" newParam2=\"1\"></Start>",
+                "<Start newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -62,7 +63,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Start>" + Environment.NewLine +
                 "  <Stream>" + Environment.NewLine +
-                "    <Parameter></Parameter>" + Environment.NewLine +
+                "    <Parameter />" + Environment.NewLine +
                 "  </Stream>" + Environment.NewLine +
                 "</Start>",
                 elem.ToString()
@@ -88,8 +89,8 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Start>" + Environment.NewLine +
-                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></Stream>" + Environment.NewLine +
-                "  <Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\"></Siprec>" + Environment.NewLine +
+                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />" + Environment.NewLine +
+                "  <Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\" />" + Environment.NewLine +
                 "</Start>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/StopTest.cs b/test/Twilio.Test/TwiML/StopTest.cs
index 7567c8f91..97259d47e 100644
--- a/test/Twilio.Test/TwiML/StopTest.cs
+++ b/test/Twilio.Test/TwiML/StopTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Stop></Stop>",
+                "<Stop />",
                 elem.ToString()
             );
         }
@@ -32,10 +32,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Stop();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Stop newParam1=\"value\" newParam2=\"1\"></Stop>",
+                "<Stop newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -51,7 +52,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Stop>" + Environment.NewLine +
                 "  <Stream>" + Environment.NewLine +
-                "    <Parameter></Parameter>" + Environment.NewLine +
+                "    <Parameter />" + Environment.NewLine +
                 "  </Stream>" + Environment.NewLine +
                 "</Stop>",
                 elem.ToString()
@@ -77,8 +78,8 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Stop>" + Environment.NewLine +
-                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></Stream>" + Environment.NewLine +
-                "  <Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\"></Siprec>" + Environment.NewLine +
+                "  <Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />" + Environment.NewLine +
+                "  <Siprec name=\"name\" connectorName=\"connector_name\" track=\"inbound_track\" />" + Environment.NewLine +
                 "</Stop>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/StreamTest.cs b/test/Twilio.Test/TwiML/StreamTest.cs
index a77bdf268..81136c30f 100644
--- a/test/Twilio.Test/TwiML/StreamTest.cs
+++ b/test/Twilio.Test/TwiML/StreamTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Stream></Stream>",
+                "<Stream />",
                 elem.ToString()
             );
         }
@@ -39,7 +39,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></Stream>",
+                "<Stream name=\"name\" connectorName=\"connector_name\" url=\"url\" track=\"inbound_track\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />",
                 elem.ToString()
             );
         }
@@ -50,10 +50,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Stream();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Stream newParam1=\"value\" newParam2=\"1\"></Stream>",
+                "<Stream newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -68,7 +69,7 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Stream>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</Stream>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/TaskTest.cs b/test/Twilio.Test/TwiML/TaskTest.cs
index f220a3a97..cce712d7e 100644
--- a/test/Twilio.Test/TwiML/TaskTest.cs
+++ b/test/Twilio.Test/TwiML/TaskTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Task></Task>",
+                "<Task />",
                 elem.ToString()
             );
         }
@@ -43,10 +43,11 @@ public void TestElementWithExtraAttributes()
             var elem = new Task();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Task newParam1=\"value\" newParam2=\"1\"></Task>",
+                "<Task newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
diff --git a/test/Twilio.Test/TwiML/VirtualAgentTest.cs b/test/Twilio.Test/TwiML/VirtualAgentTest.cs
index f96b53a9b..7c7b8a19c 100644
--- a/test/Twilio.Test/TwiML/VirtualAgentTest.cs
+++ b/test/Twilio.Test/TwiML/VirtualAgentTest.cs
@@ -21,7 +21,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<VirtualAgent></VirtualAgent>",
+                "<VirtualAgent />",
                 elem.ToString()
             );
         }
@@ -38,7 +38,7 @@ public void TestElementWithParams()
             );
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<VirtualAgent connectorName=\"connector_name\" language=\"language\" sentimentAnalysis=\"true\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\"></VirtualAgent>",
+                "<VirtualAgent connectorName=\"connector_name\" language=\"language\" sentimentAnalysis=\"true\" statusCallback=\"status_callback\" statusCallbackMethod=\"GET\" />",
                 elem.ToString()
             );
         }
@@ -49,10 +49,11 @@ public void TestElementWithExtraAttributes()
             var elem = new VirtualAgent();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<VirtualAgent newParam1=\"value\" newParam2=\"1\"></VirtualAgent>",
+                "<VirtualAgent newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -69,8 +70,8 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<VirtualAgent>" + Environment.NewLine +
-                "  <Config name=\"name\" value=\"value\"></Config>" + Environment.NewLine +
-                "  <Parameter name=\"name\" value=\"value\"></Parameter>" + Environment.NewLine +
+                "  <Config name=\"name\" value=\"value\" />" + Environment.NewLine +
+                "  <Parameter name=\"name\" value=\"value\" />" + Environment.NewLine +
                 "</VirtualAgent>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/VoiceResponseTest.cs b/test/Twilio.Test/TwiML/VoiceResponseTest.cs
index 364f12cf2..ca0f011e1 100644
--- a/test/Twilio.Test/TwiML/VoiceResponseTest.cs
+++ b/test/Twilio.Test/TwiML/VoiceResponseTest.cs
@@ -22,7 +22,7 @@ public void TestEmptyElement()
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response></Response>",
+                "<Response />",
                 elem.ToString()
             );
         }
@@ -33,10 +33,11 @@ public void TestElementWithExtraAttributes()
             var elem = new VoiceResponse();
             elem.SetOption("newParam1", "value");
             elem.SetOption("newParam2", 1);
+            elem.SetOption("xml:lang", "en");
 
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
-                "<Response newParam1=\"value\" newParam2=\"1\"></Response>",
+                "<Response newParam1=\"value\" newParam2=\"1\" xml:lang=\"en\" />",
                 elem.ToString()
             );
         }
@@ -52,7 +53,7 @@ public void TestNestElement()
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Response>" + Environment.NewLine +
                 "  <Connect>" + Environment.NewLine +
-                "    <Room></Room>" + Environment.NewLine +
+                "    <Room />" + Environment.NewLine +
                 "  </Connect>" + Environment.NewLine +
                 "</Response>",
                 elem.ToString()
@@ -100,7 +101,7 @@ public void TestElementWithChildren()
             );
 
             elem.Gather(
-                new[] {Gather.InputEnum.Dtmf},  
+                new[] {Gather.InputEnum.Dtmf},
                 new Uri("https://example.com"),
                 Twilio.Http.HttpMethod.Get,
                 1,
@@ -204,26 +205,26 @@ public void TestElementWithChildren()
             Assert.AreEqual(
                 "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
                 "<Response>" + Environment.NewLine +
-                "  <Connect action=\"https://example.com\" method=\"GET\"></Connect>" + Environment.NewLine +
+                "  <Connect action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
                 "  <Dial action=\"https://example.com\" method=\"GET\" timeout=\"1\" hangupOnStar=\"true\" timeLimit=\"1\" callerId=\"caller_id\" record=\"do-not-record\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" answerOnBridge=\"true\" ringTone=\"at\" recordingTrack=\"both\" sequential=\"true\" referUrl=\"https://example.com\" referMethod=\"GET\">number</Dial>" + Environment.NewLine +
-                "  <Echo></Echo>" + Environment.NewLine +
+                "  <Echo />" + Environment.NewLine +
                 "  <Enqueue action=\"https://example.com\" maxQueueSize=\"1\" method=\"GET\" waitUrl=\"https://example.com\" waitUrlMethod=\"GET\" workflowSid=\"workflow_sid\">name</Enqueue>" + Environment.NewLine +
-                "  <Gather input=\"dtmf\" action=\"https://example.com\" method=\"GET\" timeout=\"1\" speechTimeout=\"speech_timeout\" maxSpeechTime=\"1\" profanityFilter=\"true\" finishOnKey=\"finish_on_key\" numDigits=\"1\" partialResultCallback=\"https://example.com\" partialResultCallbackMethod=\"GET\" language=\"af-ZA\" hints=\"hints\" bargeIn=\"true\" debug=\"true\" actionOnEmptyResult=\"true\" speechModel=\"default\" enhanced=\"true\"></Gather>" + Environment.NewLine +
-                "  <Hangup></Hangup>" + Environment.NewLine +
-                "  <Leave></Leave>" + Environment.NewLine +
-                "  <Pause length=\"1\"></Pause>" + Environment.NewLine +
+                "  <Gather input=\"dtmf\" action=\"https://example.com\" method=\"GET\" timeout=\"1\" speechTimeout=\"speech_timeout\" maxSpeechTime=\"1\" profanityFilter=\"true\" finishOnKey=\"finish_on_key\" numDigits=\"1\" partialResultCallback=\"https://example.com\" partialResultCallbackMethod=\"GET\" language=\"af-ZA\" hints=\"hints\" bargeIn=\"true\" debug=\"true\" actionOnEmptyResult=\"true\" speechModel=\"default\" enhanced=\"true\" />" + Environment.NewLine +
+                "  <Hangup />" + Environment.NewLine +
+                "  <Leave />" + Environment.NewLine +
+                "  <Pause length=\"1\" />" + Environment.NewLine +
                 "  <Play loop=\"1\" digits=\"digits\">https://example.com</Play>" + Environment.NewLine +
                 "  <Queue url=\"https://example.com\" method=\"GET\" reservationSid=\"reservation_sid\" postWorkActivitySid=\"post_work_activity_sid\">name</Queue>" + Environment.NewLine +
-                "  <Record action=\"https://example.com\" method=\"GET\" timeout=\"1\" finishOnKey=\"finish_on_key\" maxLength=\"1\" playBeep=\"true\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" transcribe=\"true\" transcribeCallback=\"https://example.com\"></Record>" + Environment.NewLine +
+                "  <Record action=\"https://example.com\" method=\"GET\" timeout=\"1\" finishOnKey=\"finish_on_key\" maxLength=\"1\" playBeep=\"true\" trim=\"trim-silence\" recordingStatusCallback=\"https://example.com\" recordingStatusCallbackMethod=\"GET\" recordingStatusCallbackEvent=\"in-progress\" transcribe=\"true\" transcribeCallback=\"https://example.com\" />" + Environment.NewLine +
                 "  <Redirect method=\"GET\">https://example.com</Redirect>" + Environment.NewLine +
-                "  <Reject reason=\"rejected\"></Reject>" + Environment.NewLine +
+                "  <Reject reason=\"rejected\" />" + Environment.NewLine +
                 "  <Say voice=\"man\" loop=\"1\" language=\"arb\">message</Say>" + Environment.NewLine +
                 "  <Sms to=\"+15558675310\" from=\"+15017122661\" action=\"https://example.com\" method=\"GET\" statusCallback=\"https://example.com\">message</Sms>" + Environment.NewLine +
-                "  <Pay input=\"dtmf\" action=\"https://example.com\" bankAccountType=\"consumer-checking\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" timeout=\"1\" maxAttempts=\"1\" securityCode=\"true\" postalCode=\"postal_code\" minPostalCodeLength=\"1\" paymentConnector=\"payment_connector\" paymentMethod=\"ach-debit\" tokenType=\"one-time\" chargeAmount=\"charge_amount\" currency=\"currency\" description=\"description\" validCardTypes=\"visa\" language=\"de-DE\"></Pay>" + Environment.NewLine +
-                "  <Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\"></Prompt>" + Environment.NewLine +
-                "  <Start action=\"https://example.com\" method=\"GET\"></Start>" + Environment.NewLine +
-                "  <Stop></Stop>" + Environment.NewLine +
-                "  <Refer action=\"https://example.com\" method=\"GET\"></Refer>" + Environment.NewLine +
+                "  <Pay input=\"dtmf\" action=\"https://example.com\" bankAccountType=\"consumer-checking\" statusCallback=\"https://example.com\" statusCallbackMethod=\"GET\" timeout=\"1\" maxAttempts=\"1\" securityCode=\"true\" postalCode=\"postal_code\" minPostalCodeLength=\"1\" paymentConnector=\"payment_connector\" paymentMethod=\"ach-debit\" tokenType=\"one-time\" chargeAmount=\"charge_amount\" currency=\"currency\" description=\"description\" validCardTypes=\"visa\" language=\"de-DE\" />" + Environment.NewLine +
+                "  <Prompt for=\"payment-card-number\" errorType=\"timeout\" cardType=\"visa\" attempt=\"1\" requireMatchingInputs=\"true\" />" + Environment.NewLine +
+                "  <Start action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
+                "  <Stop />" + Environment.NewLine +
+                "  <Refer action=\"https://example.com\" method=\"GET\" />" + Environment.NewLine +
                 "</Response>",
                 elem.ToString()
             );
diff --git a/test/Twilio.Test/TwiML/XmlEscapeTest.cs b/test/Twilio.Test/TwiML/XmlEscapeTest.cs
new file mode 100644
index 000000000..509de6ee8
--- /dev/null
+++ b/test/Twilio.Test/TwiML/XmlEscapeTest.cs
@@ -0,0 +1,36 @@
+using NUnit.Framework;
+using System;
+using Twilio.TwiML.Messaging;
+
+namespace Twilio.Tests.TwiML
+{
+    [TestFixture]
+    public class XmlEscapeTest : TwilioTest
+    {
+        [Test]
+        public void TestXmlEscapedBodyMessage()
+        {
+            var elem = new Message("<InvalidBodyMessage></InvalidBodyMessage>");
+
+            Assert.AreEqual(
+                "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
+                "<Message>&lt;InvalidBodyMessage&gt;&lt;/InvalidBodyMessage&gt;</Message>",
+                elem.ToString()
+            );
+        }
+        
+        [Test]
+        public void TestXmlEscapedText()
+        {
+            var elem = new Message();
+            elem.AddText("<InvalidText></InvalidText>");
+
+            Assert.AreEqual(
+                "<?xml version=\"1.0\" encoding=\"utf-8\"?>" + Environment.NewLine +
+                "<Message>&lt;InvalidText&gt;&lt;/InvalidText&gt;</Message>",
+                elem.ToString()
+            );
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/test/Twilio.Test/Twilio.Test.csproj b/test/Twilio.Test/Twilio.Test.csproj
index 7dbe27ad0..747f9706c 100644
--- a/test/Twilio.Test/Twilio.Test.csproj
+++ b/test/Twilio.Test/Twilio.Test.csproj
@@ -2,14 +2,14 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <RootNamespace>Twilio.Tests</RootNamespace>
-    <TargetFrameworks>net6.0;net451;net35</TargetFrameworks>
+    <TargetFrameworks>net7.0;net451;net35</TargetFrameworks>
     <RuntimeIdentifier Condition=" '$(TargetFramework)' == 'net451' ">win7-x86</RuntimeIdentifier>
     <RuntimeIdentifier Condition=" '$(TargetFramework)' == 'net35' ">win7-x86</RuntimeIdentifier>
     <IsPackable>false</IsPackable>
     <GenerateProgramFile>false</GenerateProgramFile>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="coverlet.msbuild" Version="3.1.0">
+    <PackageReference Include="coverlet.msbuild" Version="3.2.0">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>