asterisk users - Feb 2005 - SER Interaction: Agents and Extensions

Hey gang,
 I'm trying to work out all possible scenarios using SER & Asterisk in
our
upcomming deployment. The example scenario is 50 different customers, all
with different numbers of SIP UAs. All UAs would register with SER; This
will help keep any inter-office conversations off our bandwidth since SER
doesn't handle the RTP stream.

 Calls from PSTN to UA are easy to handle. Asterisk receives the call on Zap
card, and forwards to SER. SER looks up in its alias table which UA to send
it to, and sends it.

 Calls from UA to PSTN are even easier. However, billing comes into question
here. If every SIP call comes "in" to Asterisk from SER, how can I
differentiate one customer from another?

 AFAIK, SER has no notion of 'context'. So, if offices wanted 4 digit
extensions, I would be unable to duplicate any extensions right?

 Onto Agents; Say I setup *80 as the AgentLogin/Logoff number for a
paticular customer. SER passes it on to Asterisk. I'd still have to setup
contexts and agents just like normal right?

 With all of these caveats, it seems to me that a SER->Asterisk solution
isn't that great. If anyone else out there can show me otherwise...

Thanks,
Matthew

Matthew Boehm wrote:
> With all of these caveats, it seems to me that a SER->Asterisk solution
>isn't that great. If anyone else out there can show me otherwise...
>
>Thanks,
>Matthew
>  
>
I think you might be missing the point here. SER is a raw SIP processor. 
So for a second throw everything you know about Asterisk + SIP out the 
window and go back to vanilla SIP. Getting used to a B2BUA in the call 
path kinda beats some of the raw power of SIP up. Think of how a SIP URI 
is formed. That domain portion is kinda like a context, right? 
furthermore, SER can "do stuff" with that.

I'm doing my own eval with SER for a very large deployment. But I'm just
getting started. I had SER running about a year ago, but it's been about 
that long since I really toyed with it.

One of the call flows I'm about to try is:
PSTN GW -> SER -> Asterisk "Transfer"/re-invite -> SER ->
Phone

The idea is that SER manages my PSTN gateway. I can always just stack 
more Asterisk servers on, SER I'll never really need to expand (there is 
a redundant SER Server, removing the need for clustering).  Then the 
call gets "sent" to asterisk for smart call processing, however actual
setup of the media gets resent back to SER. I'm not sure if I'll be able
to do this, but  I may be able to do it with re-invites. Any thoughts?
-Brett