Agree with session refresh(without o/a in specific). Makes call flow simplistic and in lots of cases avoids interoperability issues caused due to o/a wth re-invites
Thnx -----Original Message----- From: Paul Kyzivat <[EMAIL PROTECTED]> To: Manpreet Singh CC: [EMAIL PROTECTED] <[EMAIL PROTECTED]>; [EMAIL PROTECTED] <[EMAIL PROTECTED]>; sip-implementors@lists.cs.columbia.edu <sip-implementors@lists.cs.columbia.edu> Sent: Mon Apr 14 09:30:57 2008 Subject: Re: [Sip-implementors] Offer/Answer question Manpreet Singh wrote: > That's one reason why I have seen most implementations use re-invites instead > of updates for mid call changes. Why leave a possibility of 2 transactions > when one can live with 1. But then its implementation specific :-) Sometimes the call flow won't work right if a human delay is inserted in it. In that case UPDATE is ideal because it prevents that eventuality. The 3pcc call flow RFC (I forget the number) is getting a bit long in the tooth now, but it it talks about some cases with that kind of constraint. UPDATE is also useful without o/a for session timer refresh. Paul > Thnx > > -----Original Message----- > From: Brett Tate <[EMAIL PROTECTED]> > To: Manpreet Singh > CC: [EMAIL PROTECTED] <[EMAIL PROTECTED]>; > sip-implementors@lists.cs.columbia.edu > <sip-implementors@lists.cs.columbia.edu> > Sent: Mon Apr 14 09:04:10 2008 > Subject: RE: [Sip-implementors] Offer/Answer question > > I agree with Paul; however I'll highlight the rfc3311 section 5.2 text > concerning UPDATE with SDP potentially triggering a 504. Thus UAC > receiving 504 for UPDATE with SDP should be aware that a re-INVITE might > be needed to perform the SDP modification. > > "If the UAS cannot change the session parameters without prompting the > user, it SHOULD reject the request with a 504 response." > > >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On >> Behalf Of Paul Kyzivat >> Sent: Monday, April 14, 2008 12:34 AM >> To: Manpreet Singh >> Cc: Bob Penfield; [EMAIL PROTECTED]; >> sip-implementors@lists.cs.columbia.edu >> Subject: Re: [Sip-implementors] Offer/Answer question >> >> >> >> Manpreet Singh wrote: >>> Wasn't denying the use of update on confirmed dialog, just >> saying the >>> recommended use of UPDATE is for early dialog and not for confirmed >>> based on the spec. >>> >>> ""Although UPDATE can be used on confirmed dialogs, it is >> RECOMMENDED >>> that a re-INVITE be used instead. This is because an UPDATE >> needs to >>> be answered immediately, ruling out the possibility of user >> approval. >>> Such approval will frequently be needed, and is possible with a >>> re-INVITE."" >> IMO the "denial" is a bit overstated. It is only pointing out >> that its inappropriate if the offer it carries will require >> an extended time for approval before being answered. If that >> isn't to be the case then there isn't any issue with using UPDATE. >> >> Note that the issue with immediate response also applies to >> an UPDATE used during an early dialog. >> >> Paul > > _______________________________________________ > 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