diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index ebf77519f1..95f69fca14 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -5918,25 +5918,39 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req)
 			continue;
 		} else if (sscanf(a, "rtpmap: %u %[^/]/", &codec, mimeSubtype) == 2) {
 			/* We have a rtpmap to handle */
-			if (debug)
-				ast_verbose("Found description format %s for ID %d\n", mimeSubtype, codec);
-			found_rtpmap_codecs[last_rtpmap_codec] = codec;
-			last_rtpmap_codec++;
 
 			/* Note: should really look at the 'freq' and '#chans' params too */
 			/* Note: This should all be done in the context of the m= above */
 			if (!strncasecmp(mimeSubtype, "H26", 3) || !strncasecmp(mimeSubtype, "MP4", 3)) {         /* Video */
-				/* Not going to do anything here for the moment, but we will soon */
-				ast_rtp_set_rtpmap_type(newtextrtp, codec, "video", mimeSubtype, 1);
+				if(ast_rtp_set_rtpmap_type(newvideortp, codec, "video", mimeSubtype, 0) != -1) {
+					if (debug)
+						ast_verbose("Found video description format %s for ID %d\n", mimeSubtype, codec);
+					found_rtpmap_codecs[last_rtpmap_codec] = codec;
+					last_rtpmap_codec++;
+				} else {
+					ast_rtp_unset_m_type(newvideortp, codec);
+					if (debug) 
+						ast_verbose("Found unknown media description format %s for ID %d\n", mimeSubtype, codec);
+				}
 			} else if (!strncasecmp(mimeSubtype, "T140",4)) { /* Text */
 				if (p->trtp) {
 					/* ast_verbose("Adding t140 mimeSubtype to textrtp struct\n"); */
 					ast_rtp_set_rtpmap_type(newtextrtp, codec, "text", mimeSubtype, 0);
 				}
 			} else {                                          /* Must be audio?? */
-				ast_rtp_set_rtpmap_type(newaudiortp, codec, "audio", mimeSubtype,
-						ast_test_flag(&p->flags[0], SIP_G726_NONSTANDARD) ? AST_RTP_OPT_G726_NONSTANDARD : 0);
+				if(ast_rtp_set_rtpmap_type(newaudiortp, codec, "audio", mimeSubtype,
+						ast_test_flag(&p->flags[0], SIP_G726_NONSTANDARD) ? AST_RTP_OPT_G726_NONSTANDARD : 0) != -1) {
+					if (debug)
+						ast_verbose("Found audio description format %s for ID %d\n", mimeSubtype, codec);
+					found_rtpmap_codecs[last_rtpmap_codec] = codec;
+					last_rtpmap_codec++;
+				} else {
+					ast_rtp_unset_m_type(newaudiortp, codec);
+					if (debug) 
+						ast_verbose("Found unknown media description format %s for ID %d\n", mimeSubtype, codec);
+				}
 			}
+
 		}
 	}
 	
diff --git a/include/asterisk/rtp.h b/include/asterisk/rtp.h
index 56ac76e866..2aeefe0776 100644
--- a/include/asterisk/rtp.h
+++ b/include/asterisk/rtp.h
@@ -178,8 +178,14 @@ void ast_rtp_pt_default(struct ast_rtp* rtp);
 /*! \brief Copy payload types between RTP structures */
 void ast_rtp_pt_copy(struct ast_rtp *dest, struct ast_rtp *src);
 
+/*! \brief Activate payload type */
 void ast_rtp_set_m_type(struct ast_rtp* rtp, int pt);
-void ast_rtp_set_rtpmap_type(struct ast_rtp* rtp, int pt,
+
+/*! \brief clear payload type */
+void ast_rtp_unset_m_type(struct ast_rtp* rtp, int pt);
+
+/*! \brief Initiate payload type to a known MIME media type for a codec */
+int ast_rtp_set_rtpmap_type(struct ast_rtp* rtp, int pt,
 			     char *mimeType, char *mimeSubtype,
 			     enum ast_rtp_options options);
 
diff --git a/main/rtp.c b/main/rtp.c
index afaf42836b..87630f6e0e 100644
--- a/main/rtp.c
+++ b/main/rtp.c
@@ -1939,23 +1939,36 @@ void ast_rtp_set_m_type(struct ast_rtp* rtp, int pt)
 	rtp_bridge_unlock(rtp);
 } 
 
+/*! \brief remove setting from payload type list if the rtpmap header indicates
+    an unknown media type */
+void ast_rtp_unset_m_type(struct ast_rtp* rtp, int pt) 
+{
+	rtp_bridge_lock(rtp);
+	rtp->current_RTP_PT[pt].isAstFormat = 0;
+	rtp->current_RTP_PT[pt].code = 0;
+	rtp_bridge_unlock(rtp);
+}
+
 /*! \brief Make a note of a RTP payload type (with MIME type) that was seen in
  * an SDP "a=rtpmap:" line.
+ * \return 0 if the MIME type was found and set, -1 if it wasn't found
  */
-void ast_rtp_set_rtpmap_type(struct ast_rtp *rtp, int pt,
+int ast_rtp_set_rtpmap_type(struct ast_rtp *rtp, int pt,
 			     char *mimeType, char *mimeSubtype,
 			     enum ast_rtp_options options)
 {
 	unsigned int i;
+	int found = 0;
 
 	if (pt < 0 || pt > MAX_RTP_PT) 
-		return; /* bogus payload type */
+		return -1; /* bogus payload type */
 	
 	rtp_bridge_lock(rtp);
 
 	for (i = 0; i < sizeof(mimeTypes)/sizeof(mimeTypes[0]); ++i) {
 		if (strcasecmp(mimeSubtype, mimeTypes[i].subtype) == 0 &&
 		    strcasecmp(mimeType, mimeTypes[i].type) == 0) {
+			found = 1;
 			rtp->current_RTP_PT[pt] = mimeTypes[i].payloadType;
 			if ((mimeTypes[i].payloadType.code == AST_FORMAT_G726) &&
 			    mimeTypes[i].payloadType.isAstFormat &&
@@ -1967,7 +1980,7 @@ void ast_rtp_set_rtpmap_type(struct ast_rtp *rtp, int pt,
 
 	rtp_bridge_unlock(rtp);
 
-	return;
+	return (found ? 0 : -1);
 } 
 
 /*! \brief Return the union of all of the codecs that were set by rtp_set...() calls