[EMAIL PROTECTED] wrote: > Hi Andreas, > > Offer can not be in the non-reliable provisional responses. But Answer > can be in the non-reliable provisional responses.
The way I think of this is that a *preview* of the answer may be sent in a non-reliable provisional response, but the *actual* answer must come in a reliable response. By requiring that the *preview* and the *actual* answer to be the same, it is safe for the recipient to act based on the preview if it happens to get it. The reliable answer is a guarantee for the answerer that the answer will eventually be received and processed. > In theory, any SIP message can include session description in its > body. But not all the session description in a SIP message is an > offer or an answer. Only the session description that conforms to the > rules described in the standard track RFCs can be interpreted as an > offer or an answer. The rules how to handle offer/answer model are > currently defined in several RFCs. Unless defined in an RFC > explicitly as an offer or an answer, except ones in non-reliable > provisional response to INVITE request, a session description should > not be included in SIP messages to avoid confusions. > > Please refer the following Draft for more information > > http://tools.ietf.org/wg/sip/draft-sawada-sipping-sip-offeranswer-00.txt The purpose of this draft is to resolve the confusion you have, caused by incomplete specification in existing RFCs. It consolidates folklore that was developed through discussions on this list over an extended period of time. Paul > Regards, > Thangarajan. > FlextronicsSoftware > Worlds largest SIP stack vendor > > Inactive hide details for Andreas Byström > <[EMAIL PROTECTED]>Andreas Byström <[EMAIL PROTECTED]> > > > *Andreas Byström <[EMAIL PROTECTED]>* > Sent by: [EMAIL PROTECTED] > > 02/03/2006 07:59 AM > > > > To > > <[EMAIL PROTECTED]>, <[email protected]> > > cc > > > Subject > > Re: [Sip-implementors] Offer/answer retransmission OK? > > > > > This is exaclyt what I'm looking for but cant find in the specifications > (the part that SIP mandates offer/answer in reliable responses). Could you > please assist me in finding where (and in what) rfc I can find this? > > Regards, > // Andreas > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf > > Of [EMAIL PROTECTED] > > Sent: Thursday, February 02, 2006 3:31 PM > > To: [email protected] > > Subject: Re: [Sip-implementors] Offer/answer retransmission OK? > > > > > > > > > > You cannot Send SDP(answer) in a response that is not > > reliable, for the simple reason you don't get the > > Acknowledgement whether the offerer has received it or not. > > The offer/answer model in SIP mandates that the answer be > > received reliably. This is taken care by using reliable > > provisional response or by sending ACK to 2XX response. > > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:sip-implementors-> [EMAIL PROTECTED] On Behalf > > Of Andreas Byström > > Sent: > > Thursday, February 02, 2006 6:02 PM > > To: [email protected] > > Subject: [Sip-implementors] Offer/answer retransmission OK? > > > > Hi I have two SDP questions: > > > > 1. Is it (according to RFCs) ok to send the SDP answer in a > > SIP response that is not reliable? I.e, is it ok to send SDP > > in 180 (that is not using > > PRACK) > > 2. If sent in 180 (as above) is it then ok to send the exact > > same response again in 200 OK? Is it allowed to respond to a > > offer in two different mesages (first 180 and then 200). Does > > it matter if 180 is reliable (say that PRACK is used for 180, > > still ok to send SDP answer in 200?) > > > > Regards, > > // Andreas > > _______________________________________________ > > Sip-implementors mailing list > > [email protected] > > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implement > ors > > > 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. 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