diff --git a/mediainfo.go b/mediainfo.go
index 5c5b0eb..a3ec737 100644
--- a/mediainfo.go
+++ b/mediainfo.go
@@ -15,6 +15,8 @@ type MediaInfo struct {
 	simulcast     bool
 	simulcastInfo *SimulcastInfo
 	bitrate       int
+	Protocal      string
+	Payloads      string
 }
 
 func NewMediaInfo(id string, mtype string) *MediaInfo {
diff --git a/sdpinfo.go b/sdpinfo.go
index 053994d..f6d5555 100644
--- a/sdpinfo.go
+++ b/sdpinfo.go
@@ -231,6 +231,8 @@ func (s *SDPInfo) Answer(ice *ICEInfo, dtls *DTLSInfo, candidates []*CandidateIn
 		supported := medias[media.GetType()]
 		if supported != nil {
 			answer := media.AnswerCapability(supported)
+			answer.Payloads = media.Payloads
+			answer.Protocal = media.Protocal
 			sdpInfo.AddMedia(answer)
 		}
 	}
@@ -284,7 +286,7 @@ func (s *SDPInfo) String() string {
 		mediaMap := &transform.MediaStruct{
 			Type:       media.GetType(),
 			Port:       media.GetPort(),
-			Protocal:   "UDP/TLS/RTP/SAVP",
+			Protocal:   media.Protocal, // "UDP/TLS/RTP/SAVP",
 			Fmtp:       []*transform.FmtpStruct{},
 			Rtp:        []*transform.RtpStruct{},
 			RtcpFb:     []*transform.RtcpFbStruct{},
@@ -422,7 +424,15 @@ func (s *SDPInfo) String() string {
 			payloads = append(payloads, rtp.Payload)
 		}
 
-		mediaMap.Payloads = intArrayToString(payloads, " ")
+		if strings.ToLower(media.mtype) == "application" {
+			mediaMap.Payloads = media.Payloads
+			mediaMap.SctpPort = 5000
+			mediaMap.SctpMaxSize = 256 * 1024
+			mediaMap.RtcpMux = ""
+			mediaMap.RtcpRsize = ""
+		} else  {
+			mediaMap.Payloads = intArrayToString(payloads, " ")
+		}
 
 		for id, uri := range media.GetExtensions() {
 
@@ -761,6 +771,8 @@ func Parse(sdp string) (*SDPInfo, error) {
 		}
 
 		mediaInfo := NewMediaInfo(mid, media)
+		mediaInfo.Payloads = md.Payloads
+		mediaInfo.Protocal = md.Protocal
 
 		ufrag := md.IceUfrag
 		pwd := md.IcePwd
diff --git a/transform/grammer.go b/transform/grammer.go
index 1a0453a..7d42474 100644
--- a/transform/grammer.go
+++ b/transform/grammer.go
@@ -535,6 +535,32 @@ var rulesMap map[byte][]*Rule = map[byte][]*Rule{
 				}
 			},
 		},
+
+		// a=sctp-port:5000
+		&Rule{
+			Name:   "sctp-port",
+			Push:   "",
+			Reg:    regexp.MustCompile("^sctp-port:(\\d+)"),
+			Names:  []string{},
+			Types:  []rune{'d'},
+			Format: "",
+			FormatFunc: func(obj *gabs.Container) string {
+					return "sctp-port:%d"
+			},
+		},
+
+		// a=max-message-size:262144
+		&Rule{
+			Name:   "sctp-max-message-size",
+			Push:   "",
+			Reg:    regexp.MustCompile("^max-message-size:(\\d+)"),
+			Names:  []string{},
+			Types:  []rune{'d'},
+			Format: "",
+			FormatFunc: func(obj *gabs.Container) string {
+				return "max-message-size:%d"
+			},
+		},
 		// a=x-google-flag:conference
 		&Rule{
 			Name:   "xGoogleFlag",
diff --git a/transform/sdpstruct.go b/transform/sdpstruct.go
index 1daf820..26de3d6 100644
--- a/transform/sdpstruct.go
+++ b/transform/sdpstruct.go
@@ -143,6 +143,8 @@ type MediaStruct struct {
 	Candidates  []*CandidateStruct `json:"candidates,omitempty"`
 	Bandwidth   []*BandwithStruct  `json:"bandwidth,omitempty"`
 	Simulcast   *SimulcastStruct   `json:"simulcast,omitempty"`
+	SctpPort    int                `json:"sctp-port,omitempty"`
+	SctpMaxSize int                `json:"sctp-max-message-size,omitempty"`
 }
 
 type SdpStruct struct {