I have a freeswitch system that (for the most part) works flawlessly for me. However, I need to have an additional rtpmap line in the SDP when a call is answered. My client sends the following SDP upon answering the call : m=audio 17214 RTP/AVP 0 19 101 100 c=IN IP4 192.168.98.79 a=rtpmap:0 PCMU/8000 a=rtpmap:19 CN/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=rtpmap:100 X-NSE/8000 a=fmtp:100 192-194 Freeswitch forwards the following SDP to the external gateway : m=audio 20654 RTP/AVP 0 19 101 c=IN IP4 66.223.187.208 a=rtpmap:0 PCMU/8000 a=rtpmap:19 CN/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 The other information appears fine. Everything works, but my client-side is not receiving the a=rtpmap:100 line. This issue appears regardless of whether or not I'm in proxy mode, bypass mode, or neither. Using "sip_append_audio_sdp" has no effect on the answering SDP, only the initial offer. Any ideas? Thanks in advance,