> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Nabam Serbang > Sent: Wednesday, December 10, 2008 2:03 AM > To: sip-implementors@lists.cs.columbia.edu > Subject: [Sip-implementors] Offer in 2xx of INVITE > > Hi All, > > Section 13.2.2.4 of rfc 3261 says that > " If the offer in the 2xx response is not acceptable, the UAC core MUST > generate a valid answer in the ACK and then send a BYE immediately" > > I have some question on this behavior: > > 1) If the offer being presented in 2xx (200 OK) for INVITE is not acceptable > by UAC, what would be the valid answer in that ACK? Remember this not > re-INVITE which will have prior SDP.
If offer in INVITE is not acceptable, that offer can be rejected by rejecting the INVITE via 488. It is kind of overloading two things, rejecting call setup due to non acceptable offer. I do not see how it can be done when the offer is in 200 OK. So, this could be the reason why the RFC 3261 mandates an answer in ACK, which can potentially reject any m= lines. Rejecting all media is also a valid answer. As UAS doesn't want to continue with the session, (the offer is not acceptable), the UAS should BYE right away. > 2) if same offer is not acceptable by UAC, it means there is no media > streams. Why send valid answer in ACK when offer is not acceptable ? Again > sending BYE immediately means terminating the session? If you are sure to > terminate the session soon, why to send answer in ACK? Shouldn't UAS > consider that ACK has never been received and UAS send BYE rather than UAC? As I said before, the answer may reject all the m= lines in the SDP. Not sending ACK is not a good idea. This results in 200 OK being retransmitted anyway by UAS. All transactions in SIP are atomic and it should be completed. > I know the questions are multifolds rather twisted a lot, please try to > anwer my queries. > > > -- > Nabam Serbang Hope it helps, Thanks, Neel. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
