[SIPForum-discussion] [Sip-implementors] Offer in a 200OK for Invite transaction.

[Ramya Jothi]

Hi

According to Section 13.2.1 offer answer model of 3261 

1) The initial offer MUST be in either an INVITE or, if not there,
   in the first reliable non-failure message from the UAS back to
   the UAC.  In this specification, that is the final 2xx
   response.
2) 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.

>From the above what I can interpret is only if an reliable 18x has an 
answer in and incase 200Ok has a diff or same answer it will be ignored



  




-Regards 
 Ramya
" Focus on Solution not problem"
        

-----Original Message-----
From: sip-implementors-bounces at cs.columbia.edu
[mailto:sip-implementors-bounces at cs.columbia.edu] On Behalf Of Markus
Hofmann
Sent: Thursday, July 20, 2006 12:30 PM
To: someshss at yahoo.com
Cc: sip-implementors at cs.columbia.edu; Manpreet Singh;
discussion at sipforum.org
Subject: Re: [Sip-implementors] [SIPForum-discussion] Offer in a 200OK
for Invite transaction.

Hi Somesh,

I have question related to this.

What is the right behaviour (sending out INVITE with SDP offer) if SDP
in 18x (non-reliable) and 2xx are different? Sending ACK / BYE? Ignoring
2xx SDP?

Regards
Markus

Somesh S Shanbhag wrote:
> 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 <msingh at ibasis.net> 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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> 
> 
> -----------------------------------------
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> -----------------------------------------
> Somesh S. Shanbhag
> Focus Area - VoIP Team (FA-VoIP)
> Mascon Global Communication Technologies
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