Hi, does anyone have an idea why freeswitch behaves in that way? I also found something weird happening here. The debug output what freeswitch wanted to send looks okay: 2015-08-22 17:21:35.517845 [DEBUG] mod_sofia.c:780 Local SDP sofia/external/00491723764703@92.222.104.42: v=0 o=FreeSWITCH 1440225805 1440225807 IN IP4 46.38.244.168 s=FreeSWITCH c=IN IP4 46.38.244.168 t=0 0 m=audio 31090 RTP/SAVP 8 101 a=rtpmap:8 PCMA/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=ptime:20 a=sendrecv a=crypto:1 AES_CM_128_HMAC_SHA1_32 inline:v7PQBnE2o2KtZSz/PvsawsCZ4EA5QgDPcySCf01A But the sofia siptrace tells that something else has been sent, with no codec: send 901 bytes to udp/[92.222.104.42]:5060 at 17:21:35.523593: ------------------------------------------------------------------------ SIP/2.0 200 OK Via: SIP/2.0/UDP 92.222.104.42:5060;rport=5060;branch=z9hG4bK1981668796 From: "00491723764703" <sip:00491723764703@92.222.104.42>;tag=46810284 To: <sip:gw+eventphone-5849@46.38.244.168:5080;transport=udp;gw=eventphone-5849>;tag=crBj8pNgK80KH Call-ID: 1724156770@92.222.104.42 CSeq: 1223 INVITE Contact: <sip:gw+eventphone-5849@46.38.244.168:5080;transport=udp> User-Agent: FreeSWITCH-mod_sofia/1.4.20-34~64bit Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, REGISTER, REFER, NOTIFY Supported: timer, path, replaces Allow-Events: talk, hold, conference, refer Content-Type: application/sdp Content-Disposition: session Content-Length: 129 Remote-Party-ID: "5849" <sip:5849@46.38.244.168>;party=calling;privacy=off;screen=no v=0 o=FreeSWITCH 1440225805 1440225806 IN IP4 46.38.244.168 s=FreeSWITCH c=IN IP4 46.38.244.168 t=0 0 m=audio 0 RTP/AVP 19 ------------------------------------------------------------------------ I don't think the lines inbetween these two messages contain anything important but here they are: nua.c:879 nua_respond() nua: nua_respond: entering nua_stack.c:573 nua_stack_signal() nua(0x7f5fc04426a0): recv signal r_respond 200 OK nua_params.c:480 nua_stack_set_params() nua: nua_stack_set_params: entering soa.c:403 soa_set_params() soa_set_params(static::0x252ae00, ...) called soa.c:1052 soa_set_user_sdp() soa_set_user_sdp(static::0x252ae00, (nil), 0x7f5fc05f0be0, -1) called nua_session.c:2320 nua_invite_server_respond() nua: nua_invite_server_respond: entering soa.c:1270 soa_get_local_sdp() soa_get_local_sdp(static::0x252ae00, [(nil)], [0x7f5fbef62bb8], [0x7f5fbef62bb4]) called tport.c:3257 tport_tsend() tport_tsend(0x26b02e0) tpn = UDP/92.222.104.42:5060 tport.c:4046 tport_resolve() tport_resolve addrinfo = 92.222.104.42:5060 tport.c:4680 tport_by_addrinfo() tport_by_addrinfo(0x26b02e0): not found by name UDP/92.222.104.42:5060 tport.c:3594 tport_vsend() tport_vsend(0x26b02e0): 901 bytes of 901 to udp/92.222.104.42:5060 tport.c:3492 tport_send_msg() tport_vsend returned 901 Any idea why the SDP is sent out wrong and how to debug that? Thanks Nico