[SIPForum-discussion] Simultenous UPDATE Handling

[Nitin Kapoor]

Raj,

Here is what my understanding says.

In this kind of scenarios, additional rules apply to processing an UPDATE
request with an offer when the gateway has sent a 200 OK response to an
INVITE request but has not yet received an ACK. The following scenarios
generate an error response.

1) If the initial INVITE request contains an offer but does not require
provisional responses be sent reliably, then the SDP in the 200 OK is
treated like an answer. If the UAS then receives an UPDATE request before an
ACK response to the 200 OK, the UAS sends a 500 Server Internal error
response with a Retry-After header.

2) If the initial INVITE does not contain an offer and does not require
provisional responses be sent reliably, then the SDP in the 200 OK is
treated like an offer. If the UAS then receives an UPDATE request before
receiving an ACK to the 200 OK, the UAS sends a 491 Request Pending
response.

Now i might be wrong too. so lets wait for the others opinion.

Thanks,
Nitin Kapoor


On 28 May 2010 16:07, raj kumaradass <rajkumaradass at gmail.com> wrote:

> Greetings,
>
> Would like to know how the below scenario be handled, where both the ends
> of a call send UPDATE msg(inorder to switch from established audio call to
> video) simultaneously and the timing is more of alike a UPDATE response
> received for a UPDATE req sent on both the entities.
>
>
> UE-A
>                                                UE-B
>
>       ---------------------INVITE(SDPoff - audio codecs) ------------>
>
>       <--------------------180(Ringing)
> ---------------------------------------
>
>       <---------------------200 OK(SDPans - audio codecs) ---------
>
>       ---------------------UPDATE(SDPoff - Video codec) ---------->
>
>       <--------------------UPDATE(SDPoff - Video codec) ------------
>
>
> Also please suggest if any standards/links which details out on handling
> similiar scenarios.
>
>
> thankS,
> ...Raj
>
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