I believe the 200-OK in the flow is the 200-OK to the PRACK, not the INVITE.
The Calling UA should be able to handle multiple reliable provisional responses and send a PRACK for them especially in the case where the previous one was PRACK'd and the PRACK got a success response. cheers, (-:bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of WORLEY, Dale R (Dale) Sent: Wednesday, July 21, 2010 3:38 PM To: Peter Nijhuis; [email protected] Subject: Re: [Sip-implementors] retransmission of 180Ringing with require: 100rel ________________________________________ From: [email protected] [[email protected]] On Behalf Of Peter An incoming call is first ringing on a call center queue: The UAS is sending a 180 Ringing with SDP and a require: 100rel, the UAC responds with a PRACK and the UAS again with an 200 OK. Then the call is actually ringing on a UA (IP hardphone) The UAS send a 180 Ringing again with an SDP and a require:100rel, but the UAC ignores this as is seems a duplicate message. <-- INVITE/SDP supported: 100rel 100 Trying --> 180 Ringing/SDP --> Require: 100rel RSeq:1 <-- PRACK 200 OK --> 180 Ringing/SDP --> Require: 100rel RSeq:2 180 Ringing/SDP --> Require: 100rel RSeq:2 _______________________________________________ I can't imagine why the UAS sends the 3rd and 4th 180 responses -- it has already confirmed the dialog with the 200. I'm not sure if "late" provisional responses are forbidden by any specification, but I would not be surprised if the UAC does not pay any attention to them. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
