You should have a look at:
http://www.ietf.org/internet-drafts/draft-sawada-sipping-sip-offeranswer-01.txt
It would have answered this question, and may answer others you will
encounter.
Paul
Manpreet Singh wrote:
> Chris
>
> This answer was very helpful.
>
> So even when 18x carries the answer, till its reliable, the offer/answer is
> not complete. Which means 200OK MUST carry the same answer again to complete
> the offer/answer. So the 200OK SDP in this case would really be treated more
> as an answer needed to complete the offer/answer for INVITE transaction and
> both these answers MUST be identical right? Otherwise it would confuse the
> UAC.
>
> Somesh, it will only ignore other responses if the 18x was reliable. But if
> was not then it will expect the same answer to be followed in the 200OK to
> complete the offer/answer for that transaction.
>
> Manpreet
>
> -----Original Message-----
> From: Christer Holmberg (JO/LMF) [mailto:[EMAIL PROTECTED]
> Sent: Wednesday, July 19, 2006 5:43 PM
> To: [EMAIL PROTECTED]; Manpreet Singh; [EMAIL PROTECTED]
> Cc: [email protected]
> Subject: RE: [Sip-implementors] [SIPForum-discussion] Offer in a 200OK
> forInvite transaction.
>
>
> Hi,
>
> An unreliable 18x does not complete the offer/answer transaction (eventhough
> you know what the answer is), so you can't send an new offer at that point.
>
> Also, even if the 18x would be sent reliably, and complete the offer/answer
> transaction, you can not send a new offer in the 200 OK. You can have at
> most one offer/answer transaction per SIP transaction.
>
> Regards,
>
> Christer
>
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Somesh S
> Shanbhag
> Sent: 20. heinäkuuta 2006 0:27
> To: Manpreet Singh; [EMAIL PROTECTED]
> Cc: [email protected]
> Subject: Re: [Sip-implementors] [SIPForum-discussion] Offer in a 200OK
> forInvite transaction.
>
> Hi Manpreet,
>
> RFC 3261 section 13.2.1 has the following clause ...
>
> "
>
> 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.
> That same exact answer MAY also be placed in any provisional responses sent
> prior to the answer. The UAC MUST treat the first session description it
> receives as the answer, and MUST ignore any session descriptions in
> subsequent responses to the initial INVITE "
>
> So, UAC MUST treat 183 session progress as the answer and shall ignore in
> subsequent responses to INVITE.
>
> Hope this helps
> Thanks
> Somesh S. Shanbhag
>
>
>
> Manpreet Singh <[EMAIL PROTECTED]> wrote: For the INVITE
> transaction where the offer was sent in an INVITE and the answer coming back
> in 183, would it be valid to send a new offer in the 200OK? So the
> question is whether the 200OK can be used to send a "new" Offer (
> different from the answer in 183 ) for the INVITE transaction once 183 has
> completed the offer/answer part of that transaction. Only UPDATE can be
> used for early dialog changes as per my understanding and a 200OK still
> constitutes early dialog so it wont be valid to send a new offer in 200OK?
> Although 200OK can carry the same SDP as 183 which would mean nothing or
> would not be considered as early dialog change in capability.
>
> Please correct me if I am wrong.
>
> Thanks
>
> Manpreet
> _______________________________________________
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>
>
>
> -----------------------------------------
> SIMPLICITY IS THE BEAUTY.
> BE NATURAL LIVE NATURAL.
> -----------------------------------------
> Somesh S. Shanbhag
> Focus Area - VoIP Team (FA-VoIP)
> Mascon Global Communication Technologies Enterprise of Mascon Global Limited
> #59/2, 100Ft Ring Road Banashankari II stage Bangalore-560070 Karnataka
> INDIA
> Website: http://www.mgl.com/
> -----------------------------------------
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