There is nothing to prevent a proxy from being "dialog aware" / "dialog
stateful". If it wants to be dialog stateful it needs to Record-Route so
that it is privy to mid-dialog signaling.
But there are limits to what is possible with a proxy that is conformant
to 3261. In particular, the proxy cannot initiate new requests (e.g.
BYE) in the dialog. So it is dependent on the UAs to initiate requests.
If you need to initiate requests within the dialog then the only valid
way to do so is to be a UA. If you want to be "proxy-like' in this case
then you will be a B2BUA. Such a thing is typically called an SBC.
Thanks,
Paul
On 12/3/2010 6:29 AM, Iñaki Baz Castillo wrote:
> 2010/12/3 Vadim Lebedev<[email protected]>:
>>
>> I wonder what is the best strategy to adopt in folowing scenarios:
>>
>> 1. Endpoint A sends INVITE to B through stateful proxy P
>> 2. B responds with 100 then with 180 which are succesuflly deliverd to A
>> 3.1 B sends 200
>> 3.2 P decides that it needs to drop the call (Because of dread media
>> gateway detection for example)
>> What would be the best strategy for P?
>> It seems that it can send 6xx to A but what it is supposed to
>> send to B? a BYE?
>
> A proxy, by definition, cannot act in this case.
>
>
>
>> The second scenario is:
>> 1. Endpoint A sends INVITE to B through stateful proxy P
>> 2. B responds with 100 then with 180 which are succesuflly deliverd to A
>> 3 B sends 200 which is delivered to A
>> 4. P decides that it needs to drop the call.
>> What would be the best strategy for P in this case?
>
> Again a proxy (transaction stateful proxy) is not dialog aware so it's
> not capable of terminating a dialog (it doesn't know about current
> dialogs).
>
> However some proxies are "dialog" aware (just limitations) and can
> generate a BYE for each participant in the dialog (your second case).
> For the first case there is no way in a proxy.
>
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