Hi Brett, Thanks a lot for your reply. Below is my understanding, please advise if it is correct.
> I have call flow like where Vendor sends > 183 w/SDP included Rseq and customer sents > the PRACK and 200 OK from vendor. > > After that vendor is again sending 1~2 > 183 w/SDP where it is not changing anything > in SDP but only asking for PRACK by sending RSEQ. > I checked the RFC , but cannot see anything like > which says UAS cannot send multiple 183 w/SDP. Concerning the additional 18x messages, I assume that To tags did not change and that the RSeq value was incremented. *## Yes you are correct. Only Rseq Value is increasing, TO tag is same for all 183.* > Can you please help on this, whether any UAS can > send multiple 183 w/SDP where it is asking for PRACK? > Is it valid call flow, because i cannot see > anything RFC. RFC 6337 section 3.1.1 indicates the following (F9 is second 18x when prior 18x contained answer SDP): "The UAS does not include SDP in responses F9 and F12. However, the UAC should prepare to receive SDP bodies in F9 and/or F12, and just ignore them, to handle a peer that does not conform to the recommended implementation." *### As per this paragraph and i checked the RFC..Which means UAS can send additional 183 w/SDP or RSEQ, and UAC simply can ignore this.* Please advise if my understanding is correct. Regards, Nitin Kapoor On Thu, Jul 10, 2014 at 12:50 PM, Brett Tate <br...@broadsoft.com> wrote: > > I have call flow like where Vendor sends > > 183 w/SDP included Rseq and customer sents > > the PRACK and 200 OK from vendor. > > > > After that vendor is again sending 1~2 > > 183 w/SDP where it is not changing anything > > in SDP but only asking for PRACK by sending RSEQ. > > I checked the RFC , but cannot see anything like > > which says UAS cannot send multiple 183 w/SDP. > > Concerning the additional 18x messages, I assume that To tags did not > change and that the RSeq value was incremented. > > > > Can you please help on this, whether any UAS can > > send multiple 183 w/SDP where it is asking for PRACK? > > Is it valid call flow, because i cannot see > > anything RFC. > > RFC 6337 section 3.1.1 indicates the following (F9 is second 18x when > prior 18x contained answer SDP): > > "The UAS does not include SDP in responses F9 and F12. However, the > UAC should prepare to receive SDP bodies in F9 and/or F12, and just > ignore them, to handle a peer that does not conform to the > recommended implementation." > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
