In theory, any SIP message can include a session description in its body. But a session description in a SIP message is not necessarily an offer or an answer.
Refer to Section 2.1.2 of draft-ietf-sipping-sip-offeranswer-01 Summarizing:- When the INVITE request does not have an SDP, * The first 1xx-rel MUST contain an SDP as the offer. * The first 1xx (unreliable) MAY/MAY NOT include an SDP but it is not the official offer (if included). It may be used as a preview for the offer that'll subsequently follow. I hope this helps. Regards, Gaurav > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sip- > [EMAIL PROTECTED] On Behalf Of Stephen Paterson > Sent: Thursday, July 05, 2007 5:14 PM > To: [EMAIL PROTECTED] > Subject: [Sip-implementors] INVITE with no SDP - provisional response > withSDP > > Hi all, > > Is it at all meaningful for an unreliable 1xx response to an INVITE to > contain an SDP body when the INVITE itself did not? I'm aware of the > situation in the reliable case. > I'm rather hoping that this is not allowed for the sake of making my > life easier but alas, I suspect it is. I certainly can't think of any > use for it as there is no means for the UAC to provide an answer before > it receives the final response. I also can't find anything in the RFCs > that mentions this situation in any way. If I've missed it, please just > point me to the relevant section of the RFCs. That should be all I need. > > Thanks > > Steve > > Steve Paterson > Software Engineer > Aculab > Tel: +44 (0) 1908 273866 > Fax: +44 (0) 1908 273801 > Email: mailto:[EMAIL PROTECTED] > Website: http://www.aculab.com > > > > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 > 1PT, UK > Registration No: 1397386 (Wales) > P Please consider the environment and don't print this e-mail unless you > really need to > _______________________________________________ > 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
