Hello, My freeswitch's INVITE sdp offers two m=audio lines. (RTP/SAVP and RTP/AVP). That's OK, because I want it so ;) But both use the same audio port number. ** Is that possible to change this behavior ? To use different audio port numbers for each m=audio line ... Please check my example below. In SDP from my freeswitch, both m-lines have *m=audio **22284*. The reason, why I want to change this is WebRTC and RTPengine. RTPengine changes this INVITEs to RTP/SAVPF. And the changed RTP/SAVPF is then not acceptable for chrome browsers. Firefox works well (so far). I already reported this to the RTPengine but they say the problem is with INVITE from freeswitch because the m-audio lines use the same port. My example : incoming calls -> Media Server (freeswitch) -> Kamailio (sip and websocket proxy) -> WebRTP and SIP clients I have found a feature *media_webrtc=true* so I could avoid using rtpengine for webrtc clients (that would be really awesome), but then classic sip clients are offered only with RTP/SAVPF and most sip phones do not know RTP/SAVPF so the calls are rejected :( INVITE SDP from freeswitch: v=0. o=SBC 1464589775 1464589776 IN IP4 <freeswitch-public-ip>. s=SBC. c=IN IP4 <freeswitch-public-ip>. t=0 0. *m=audio 22284 RTP/SAVP 8 0 9 3 18.* a=rtpmap:8 PCMA/8000. a=rtpmap:0 PCMU/8000. a=rtpmap:9 G722/8000. a=rtpmap:3 GSM/8000. a=rtpmap:18 G729/8000. a=rtcp:22285 IN IP4 <freeswitch-public-ip>. a=crypto:1 AEAD_AES_256_GCM_8 inline:Q/O+iUzZ9AZLcrADA7w/XcpkmuW6yArr1vsaWc0coTyWUIRLX2qfCA7XDAs. a=crypto:2 AEAD_AES_128_GCM_8 inline:mBb/SmBuSQNSm8lC5giUfZMCv0ZYINvsQiX2sw. a=crypto:3 AES_CM_256_HMAC_SHA1_80 inline:ahOTNSsdmHLIOBqvUyGyNjd+gDfAE/+jA6w7XwzGWxBMjtzf5akXNvM/OGy0jQ. a=crypto:4 AES_CM_192_HMAC_SHA1_80 inline:k7002pXV/SUT7JHhZTYaMV5keUTp1EP57M4rcNZnAoZZzsceTXA. a=crypto:5 AES_CM_128_HMAC_SHA1_80 inline:bHcV4E/OnzMkNeaFplPWt4RELILYZeGlifnJNlRV. a=crypto:6 AES_CM_256_HMAC_SHA1_32 inline:zJkowU1tc5rQR5BPpg2m3eE97ZqXLFFJc1Agh89XuZynPFMrXhO266+eMZCd2A. a=crypto:7 AES_CM_192_HMAC_SHA1_32 inline:2DwGI3UAPsLFBS5sJBsc+pzEsITQwDHCvB0u7pK/XEE3G8swsrw. a=crypto:8 AES_CM_128_HMAC_SHA1_32 inline:Jen6Gm56Z+4RTRmfpXTpSpoG5bduyythl1j21a15. a=crypto:9 AES_CM_128_NULL_AUTH inline:Nn83liGQY7eY8LGs9qz/7EoPiHOpRgwY8H7Ts/b5. a=ptime:20. *m=audio 22284 RTP/AVP 8 0 9 3 18.* a=rtpmap:8 PCMA/8000. a=rtpmap:0 PCMU/8000. a=rtpmap:9 G722/8000. a=rtpmap:3 GSM/8000. a=rtpmap:18 G729/8000. a=rtcp:22285 IN IP4 <freeswitch-public-ip>. a=ptime:20. INVITE SDP from RTPengine : v=0 o=SBC 1464589775 1464589776 IN IP4 212.232.17.66 s=SBC c=IN IP4 <rtpengine-public-ip> t=0 0 *m=audio 31836 RTP/SAVPF 8 0 9 3 18* a=rtpmap:8 PCMA/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:9 G722/8000 a=rtpmap:3 GSM/8000 a=rtpmap:18 G729/8000 a=ptime:20 a=sendrecv a=rtcp:31837 a=setup:actpass a=fingerprint:sha-1 11:76:2D:2A:F7:0D:5A:23:9D:F6:0C:E7:4C:DF:1E:CB:BF:5D:76:4F a=ice-ufrag:NauDcjVU a=ice-pwd:AiHk6LF4tE0GElyFMWtLeod1wH a=candidate:cE0FGbXWIfwj6OGD 1 UDP 2130706431 <rtpengine-public-ip> 31836 typ host a=candidate:cE0FGbXWIfwj6OGD 2 UDP 2130706430 <rtpengine-public-ip> 31837 typ host *m=audio 31866 RTP/SAVPF 8 0 9 3 18* a=rtpmap:8 PCMA/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:9 G722/8000 a=rtpmap:3 GSM/8000 a=rtpmap:18 G729/8000 a=ptime:20 a=sendrecv a=rtcp:31867 a=setup:actpass a=fingerprint:sha-1 11:76:2D:2A:F7:0D:5A:23:9D:F6:0C:E7:4C:DF:1E:CB:BF:5D:76:4F a=ice-ufrag:YxCyPhQV a=ice-pwd:2vYt8YaMhIp2DSLPeYOKDqqBX0 a=candidate:cE0FGbXWIfwj6OGD 1 UDP 2130706431 <rtpengine-public-ip> 31866 typ host a=candidate:cE0FGbXWIfwj6OGD 2 UDP 2130706430 <rtpengine-public-ip> 31867 typ host