I agree with Paul with addition that If the offer in INVITE has got answer in 180, SDP in PRACK is optional unless UAC want to change the media stream. You can have early dialog even before PRACK transation is completed. However, if you have new "m=" lines that is not present in answer (one came with 180), that means you want to change media stream. New media streams, after transaction has completed, depends on reaction of UAS with that new "m=" line. If UAS accepts new "m=" line, it will present another answer in 200 OK of PRACK else both UAs will be using earlier negotiated SDP. PRACK request is for reliability of provisional responses. As such SDP in PRACK is optional.
Thanks and regards Nabam Serbang -----Original Message----- From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Paul Kyzivat Sent: Friday, December 19, 2008 11:35 PM To: pravin.sw...@wipro.com Cc: sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip-implementors] PRACK -200 OK / Offer Answer Model pravin.sw...@wipro.com wrote: > HI.. All, > > In the below scenario Is offer /Answer Still required Even if its > completed in INV & 180 ??. > > Understanding Early Dialog Establishment is it right way to send PRACK > request & response without SDP. ?? > > > UAC UAS > > INV(offer) > ----------------------------------------------> > 180(Answer) > <--------------------------------------------- > PRACK ( SDP/OFFER still required ???) > -----------------------------------------------> I assume that INV had Supported:100rel and 180 had Required:100rel. If so, then the PRACK itself is required, but it need not have an offer. > 200 OK (SDP/Answer still required ????) > <--------------------------------------------- The 200 for the PRACK must have an answer if and only if the PRACK had an offer. Sounds like you haven't seen https://datatracker.ietf.org/drafts/draft-ietf-sipping-sip-offeranswer Paul > 200 OK(INV) > <--------------------------------------------- > ACK > -----------------------------------------------> > > Reagrds > P.S. > > Please do not print this email unless it is absolutely necessary. > > The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. > > WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. > > www.wipro.com > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
