2009/4/30 Pranab Bohra <[email protected]>:
> Hi,
>
> Following is the call flow (based on the traces taken at UA1 and UA2):
>
> 1. UA1 sends offer to UA2 (proxy)
> 2. UA2 forwards the offer in INVITE to another proxy UA3
> 3. UA3 answers to the offer with a held SDP in 200 response (because
> it probably does not yet know who is going to receive the call
> eventually)

Sorry for my English, but what does "held SDP" mean?


> 4. UA2 ACKs the 200 response

¿?¿ A proxy CANNOT send an ACK for a received 200!!
Are you sure you mean "proxies"?


> 5. UA3 sends INVITE back to UA2 immediately, this time with an updated SDP.

Sorry, I'm completely lost. In step 3, UA3 received the INVITE and
"auto"-generated a 200 Ok, what do you mean know with "UA3 sends
INVITE back to UA2 immediately"?


> The question is - In response to the last offer by UA3, what should
> the UA2's reply ? Can it send the same SDP that it had sent in step 2
> ?
>
> My concern is, if it does so, wouldn't UA3 discard it as a duplicate SDP ?

I've understood basically nothing, so the only I can say is the following:
- The SDP CANNOT change during an early-dialog (same To tag). So if a
UAS sends 180/183 with a SDP, it CANNOT send later a 200 with a
different SDP.
But probably it has nothing to do with your scenario.

-- 
Iñaki Baz Castillo
<[email protected]>

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