Hi Kumar,
Yes you are correct. The UAS can not initiate subsequent offer if it has
already sent or received answer of offer in initial transaction.
Reference Refer RFC 3261:
Once the UAS has sent or received an answer to the initial
offer, it MUST NOT generate subsequent offers in any responses
to the initial INVITE. This means that a UAS based on this
specification alone can never generate subsequent offers until
completion of the initial transaction.
Thanks and Regards,
Vivek Talwar
On Fri, Jul 27, 2012 at 4:41 PM, <kumar.ramad...@wipro.com> wrote:
> Hi *,
>
> Whether below mentioned scenarios correct from Offer/Answer model point of
> view ?
>
>
> 1. INVITE/18x (Reliable) for Offer/Answer1.
>
> 200 OK (INVITE)/ACK for Offer/Answer2.
>
> 2. INVITE/18x (Reliable) for Offer/Answer1.
>
> PRACK/200 OK (PRACK) for Offer/Answer2.
> 200 OK (INVITE)/ACK for Offer/Answer3.
>
> 3. INVITE/18x (Reliable) for Offer/Answer1.
>
> UDPATE/200 OK (UPDATE) for Offer/Answer2.
>
> 200 OK (INVITE)/ACK for Offer/Answer3.
>
> 4. INVITE/18x (Reliable) for Offer/Answer1.
>
> PRACK/200 OK (PRACK) for Offer/Answer2.
>
> UDPATE/200 OK (UPDATE) for Offer/Answer3.
>
> 200 OK (INVITE)/ACK for Offer/Answer4.
>
> My doubt is mainly for the case, where Offer is received in 200 OK (of
> INVITE) (later Answer in ACK), as already the offer/answer exchange has
> happened for that SIP transaction via INVITE/18x(reliable).
> I have read somewhere, that there should be only one offer/answer exchange
> for a SIP transaction.
> Please clarify.
>
> Thanks,
> kumar
>
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