Hi all I'm using freeswitch to call from browser(webrtc) to some sip provider. So, the A-keg is webrtc opus codec and then I bridge it with the sip gateway. Sip gateway supports g711 only. And it chooses wrong codec and DTMF is not working between them. When bridging to sip, freeswitch sends such SDP 72a02659-6c1b-424e-b76a-0a9b16aecc2a Local SDP: 72a02659-6c1b-424e-b76a-0a9b16aecc2a v=0 72a02659-6c1b-424e-b76a-0a9b16aecc2a o=FreeSWITCH 1509346805 1509346806 IN IP4 x.x.x.x 72a02659-6c1b-424e-b76a-0a9b16aecc2a s=FreeSWITCH 72a02659-6c1b-424e-b76a-0a9b16aecc2a c=IN IP4 x.x.x.x 72a02659-6c1b-424e-b76a-0a9b16aecc2a t=0 0 72a02659-6c1b-424e-b76a-0a9b16aecc2a m=audio 31568 RTP/AVP 102 9 0 8 103 101 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:102 opus/48000/2 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=fmtp:102 useinbandfec=1; maxaveragebitrate=14400; maxplaybackrate=8000; sprop-maxcapturerate=8000; ptime=20; minptime=10; maxptim e=40; stereo=1 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:9 G722/8000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:0 PCMU/8000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:8 PCMA/8000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:103 telephone-event/48000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=fmtp:103 0-16 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:101 telephone-event/8000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=fmtp:101 0-16 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=ptime:20 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=sendrecv Is it possible to send SDP without opus rtpmap? Because SIP gateway choose wrong telephone-event. the answer of sip gateway is 72a02659-6c1b-424e-b76a-0a9b16aecc2a 2017-10-30 15:46:13.248384 [DEBUG] sofia.c:7058 Remote SDP: 72a02659-6c1b-424e-b76a-0a9b16aecc2a v=0 72a02659-6c1b-424e-b76a-0a9b16aecc2a o=lvp 8000 8000 IN IP4 y.y.y.y 72a02659-6c1b-424e-b76a-0a9b16aecc2a s=SIP Call 72a02659-6c1b-424e-b76a-0a9b16aecc2a c=IN IP4 y.y.y.y 72a02659-6c1b-424e-b76a-0a9b16aecc2a t=0 0 72a02659-6c1b-424e-b76a-0a9b16aecc2a m=audio 22786 RTP/AVP 8 103 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:8 PCMA/8000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=rtpmap:103 telephone-event/48000 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=fmtp:103 0-16 72a02659-6c1b-424e-b76a-0a9b16aecc2a a=ptime:20 I guess there must be a=rtpmap:101 telephone-event/8000 Thanks