[asterisk-users] Asterisk vs FreeSwitch vs Asterisk + OpenSIP

[Brynjolfur Thorvardsson]

I hope I'm not flogging a dead horse here, but the discussion around the whole scalability issue in Asterisk have opened my eyes to a whole lot of issues, making me increasingly confused!

We have a fully functioning and stable installation where we offer PBX services to some 15 small firms (basically medical practices). These are based all over the country, with between 2 and 15 SIP phones each. We have a Web front end where each firm can configure their own queues, menus, forwarding etc.

My problem is that my bosses want to expand massively, they are currently talking of at least a tenfold increase in the number of clients. I'm fairly certain our Asterisk server won't be able to handle that. Our current 15 clients all have peak usage at the same time (with 2/3 of all traffic between 8 and 9 in the morning). At peak times, we have 20% CPU load with some 100 concurrent calls and a little under one call/second.

I have to solve the scalability problem within a relatively short timeframe so starting from scratch with something new is out of the question.

My first thought was to add another Asterisk server and use DUNDi load balancing between the two. But looking around and reading the discussion on this list got me to thinking whether some sort of SIP switch or router/proxy could take some load off the Asterisk server(s).

One of my main concerns is to change our current setup as little as possible. It's a mishmash of Asterisk, MySQL, Rails and RAGI/RAMI. The original programmers are no longer available to me and I am still very wet behind the ears when it comes to VOIP.

So should I be looking at adding e.g. OpenSIP as a sip proxy to our current setup or adding a second (and then a third and a fourth ...) Asterisk server with DUNDi? Or both? Will adding OpenSIP require a change in the way in which we handle SIP peers or require some major reconfiguration of Asterisk? It seems to me that DUNDi requires minimal configuration changes but I don't really know.

Any information and recommendations will be greatly appreciated!

Regards

Binni