RFC 3261 Section 13.2.1 also says "Concretely, the above rules specify two exchanges for UAs compliant to this specification alone - the offer is in the INVITE, and the answer in the 2xx (and possibly in a 1xx as well, with the same value), or the offer is in the 2xx, and the answer is in the ACK."
This gives an idea that the 2xx also carries the answer SDP though a 1xx response has carried the same value before. So, it wud be great if someone could point out where "optional" is mentioned. -- Thanks, Hema Ramesh. Stephen Paterson wrote: >Thanks Darshan, > >It is the fact that we require the presence of an SDP body that is the >problem - i.e. calls fail to UAs that place the SDP in a reliable >provisional response but not the subsequent 200. If this is an option where >a reliable answer has been sent then we are out of spec. What I'm looking >for is where this behaviour is defined. I don't think the RFCs are clear on >the subject:- > >RFC 3261 13.2.1 2nd bullet > >'If the initial offer is in an INVITE, the answer MUST be in a reliable >non-failure message from UAS back to UAC which is correlated to that INVITE. >For this specification, that is only the final 2xx response to that INVITE.' > >This suggests, for an implementation covering 3261 as all UAs must, the 200 >must contain an SDP body. > >As I understand it, behaviour defined by 3261 will not change unless >explicitly stated by an extension to SIP. Now, the extension in question is >RFC 3262 (Reliability of Provisional Responses) and nowhere in this RFC does >it modify the behaviour of the 200 response to the INVITE. In fact it >explicitly states that the same rules are followed as defined in section >13.2 of RFC3261. > >I'm fairly sure now that SDP in a 200 response to INVITE is optional and >certainly the general consensus of the SIP implementors is that it is >optional but I do need to know where this is stated in the RFCs. > >Please can someone point me in the right direction. > >Regards > >Steve > >-----Original Message----- >From: Darshan Bildikar [mailto:[EMAIL PROTECTED] >Sent: 17 February 2006 10:56 >To: 'Stephen Paterson'; [email protected] >Subject: RE: [Sip-implementors] Where in the specs? > > >The 200 OK CAN contain an SDP even if a reliable 1XX contained an SDP. The >proviso being that it must remain unchanged from the SDP answer in the 1XX >response (since the offer answer is already complete). > >So your implementation isn't actually "incorrect" but it shouldn't require >the SDP in 200 OK if the offer answer has already been exchanged before. > >Someone correct me if I'm wrong. > > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Stephen >Paterson >Sent: Friday, February 17, 2006 4:11 PM >To: '[email protected]' >Subject: [Sip-implementors] Where in the specs? > >Hi all, > >In a previous thread (No SDP in 200 reply to INVITE), Nataraju A.B. wrote: > >'If the 1xx responses were sent reliably then it's optional to carry the SDP >in 200 responses.' > >I can't for the life of me find in the RFCs where this is stated. Please >could you enlighten me. >Currently our implementation requires that all 200 responses contain an SDP >body but it seems from this thread that this behaviour is incorrect when any >1xx + SDP response was sent reliably. > >Thanks in advance. > >Steve > >Steve Paterson >Aculab >Tel: +44 (0) 1908 273866 >Fax: +44 (0) 1908 273801 >Email: mailto:[EMAIL PROTECTED] >Website: http://www.aculab.com > >_______________________________________________ >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 > > > > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
