How H.323 to SIP Calls Work
For H.323 to SIP IWF calls, if 2833-related information is to be sent in the INVITE, the SIP interface of the SIP session agent has to be configured with the rfc2833-mode parameter set to preferred.
The following example shows an INVITE without 2833 in the SDP:
Apr 5 04:28:50.073 On 127.0.0.1:5070 sent to 127.0.0.1:5060 INVITE sip:780@192.168.200.6:5060 SIP/2.0 Via: SIP/2.0/UDP 127.0.0.1:5070;branch=z9hG4bKIWF0000gl2018604agg71c0;acme_irealm=external;acme_sa=192.168.1.6 Contact: "jdoe"<sip:127.0.0.1:5070> GenericID: 114421133000000@000825010100 Supported: 100rel^M From: "msmith"<sip:192.168.200.68:5060>;tag=000000ab00011940 To: <sip:780@192.168.200.6:5060> Call-ID: 7f00000113ce000000ab000101d0@127.0.0.1 CSeq: 2 INVITE Content-Length: 225 Content-Type: application/sdp v=0 o=IWF 3 3 IN IP4 192.168.1.6 s=H323 Call c=IN IP4 192.168.1.6 t=0 0 m=audio 5214 RTP/AVP 0 18 a=rtpmap:0 PCMU/8000/1 a=rtpmap:18 G729/8000/1 a=fmtp:18 annexb=no m=video 5216 RTP/AVP 31 a=rtpmap:31 H261/9000/1