Hallo, we have the following fax scenario: Asterisk(SIP provider) => Freeswitch => Auerswald COMmander 6000R PBX IPS 10.10.10.10 => 20.20.20.20 => 30.30.30.30 Fax is initiated by Asterisk with PCMA codec Auerswald connects with PCMA and then does a T.38 reinvite In the T.38 reinvite Auserwald PBX sends a m=audio 0 RTP/AVP 19 m=image 49376 udptl t38. Freeswitch then finally drops most of the SDP and answers with m=image 0 udptl t38. m=image 0 udptl t38. and Auerwald PBX hangs up Anybody has an idea what is causing this? Why is Freeswitch not forwarding the complete SDP message. Maybe the "m=audio 0" is causing the problem? Dialplan is just sip_copy_multipart=false and bridge In internal and external profile <param name="t38-passthru" value="true"/> is set. Freeswitch log shows in between: 2014-02-10 13:23:10.869112 [INFO] sofia.c:5543 Activating T38 Passthru ========= Here are the SDPs================== SDP from Reinvite Auerswald to Freeswitch v=0. o=- 5045970593938686503 4940450077875186463 IN IP4 30.30.30.30. s=-. c=IN IP4 30.30.30.30. t=0 0. m=audio 0 RTP/AVP 19. m=image 49376 udptl t38. a=T38FaxVersion:0. a=T38MaxBitRate:14400. a=T38FaxUdpEC:t38UDPRedundancy. a=T38FaxUdpEC:t38UDPFEC. a=T38FaxRateManagement:transferredTCF. a=T38FaxMaxDatagram:512. a=T38FaxMaxBuffer:1472. SDP from Invite Freeswich to Asterisk: v=0. o=FreeSWITCH 1392015640 1392015642 IN IP4 20.20.20.20. s=FreeSWITCH. c=IN IP4 20.20.20.20. t=0 0. m=image 19342 udptl t38. a=T38FaxVersion:0. a=T38MaxBitRate:14400. a=T38FaxRateManagement:transferredTCF. a=T38FaxMaxBuffer:1472. a=T38FaxMaxDatagram:512. a=T38FaxUdpEC:t38UDPFEC. SDP from Ok from Asterisk to Freeswitch: v=0. o=root 1238355194 1238355195 IN IP4 10.10.10.10. s=Asterisk PBX 11.0.1. c=IN IP4 10.10.10.10. t=0 0. m=image 4609 udptl t38. a=T38FaxVersion:0. a=T38MaxBitRate:14400. a=T38FaxRateManagement:transferredTCF. a=T38FaxMaxDatagram:702. a=T38FaxUdpEC:t38UDPFEC. SDP from 200 OK from Freeswitch to Auerswald: v=0. o=FreeSWITCH 1392020936 1392020938 IN IP4 20.20.20.20. s=FreeSWITCH. c=IN IP4 20.20.20.20. t=0 0. m=image 0 udptl t38. m=image 0 udptl t38. Auerswald sends a BYE with Reason: SIP;cause=488;text="Not Acceptable Here". -- With kind regards Peter Steinbach Telefaks Services GmbH mailto:lists (att) telefaks.de Internet: www.telefaks.de