Hi all, I meet a weird case with precondition but can not find any document talk about it:
I make SIP call from my system to the fax machine. In the initial INVITE, my system includes precondition in Supported header and status in SDP. But fax machine does not support precondition so it removes precondition from Supported header and status from SDP. After voice call is established, fax machine sends T.38 re-INVITE to my system to start fax with Supported header has no precondition and SDP has no status. And my system answers fax machine by 200 OK with Supported has precondition and T.38 SDP has status for precondition: m=image 55314 udptl t38 a=T38FaxVersion:0 a=T38MaxBitRate:14400 a=curr:qos local sendrecv a=curr:qos remote sendrecv a=des:qos none local sendrecv a=des:qos none remote sendrecv Is it the acceptable behavior? and there is any document talk a bout this case? with re-INVITE for voice all and for fax call, the behaviors are the same or different? I really appreciate your advice Thanks and regards, A.C _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
