[SR-Users] [Sems] Solutions to missing BYEs, accounting for them

[Alex Balashov]

On 04/23/2010 05:18 AM, Raphael Coeffic wrote:
> On 23.04.10 09:51, Alex Balashov wrote:
>> On 04/22/2010 10:01 AM, Stefan Sayer wrote:
>> ]
>>> clean? I am not so sure any more, trying to hack something together to
>>> see where this gets. Is there a clean and simple method to do re-invite
>>> from the b2bua, which catches all the possibilities (changed session
>>> etc)?
>>>
>>> e.g., one possibility, reinvite with last SDP from the other side
>>
>> From my understanding of SSTs, this is the correct approach (last
>> known SDP). This has the advantage of not breaking the changes of real
>> re-INVITEs that actually happened.
>>
> Sending an empty INVITE has the appeal of working with either side (no
> matter with which you begin). With the other, you might have to remember
> which side initiated the last INVITE or UPDATE transaction, and send the
> last positive SDP answer to this side as a re-INVITE. Or am I missing
> something?
>
> However, it might happen that the one of the ends does not support
> receiving empty INVITEs... (less probable today).

I thought about empty INVITEs first, but my--admittedly naive--reading 
of the specs suggests that many endpoints would take the absence of an 
SDP offer/answer in a sequential request or reply within the same 
session to mean that the media elements of the session have been 
rescinded.

If I'm wrong, that would certainly make all this a lot easier.

-- 
Alex Balashov - Principal
Evariste Systems LLC
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