[Serusers] SER + B2BUA

[Klaus Darilion]

Alex Bligh wrote:
> 
> 
> --On 29 March 2004 10:38 +0200 Klaus Darilion 
> <klaus.mailinglists at pernau.at> wrote:
> 
>> You can't make 1. without a B2BUA. Who else will disrupt the call in case
>> of zero balance?
> 
> 
> Perhaps I am missing something, but why not either
> a) The media gateway, or

Are there gateways which can tear down active calls on bevave of some 
other component? Another problem ocours if the gateway does not belong 
to you (using a SIP-PSTN-termination provider).

> b) Assuming you have a stateful proxy, the proxy server (with suitable
>   hackery) - how would the UA/proxy upstream/downstream from the proxy
>   *know* if the proxy really received a BYE, or just faked one up? So
>   if you send one BYE in each direction, you get two ACK packets produced
>   which would perhaps confuse their final recipient, except the proxy
>   server will eat them.

You would need a call staful proxy (ser is only transaction stateful). 
The proxy would have to generate the BYE messages - so per definition - 
it is no more a proxy, because proxies don't generate requests on their 
own, they just forward requests. So this thing must be called B2BUA.

Klaus