Asterisk scalability as conference bridge

I have a question for everybody regarding scalability in a particular scenario. Basically I have been tasked with looking at the potential ways my company could setup a conference bridge system to lower conference costs (currently well into 5 figures per month) with a target of 350 Simultaneous users with some being PSTN connected and some SIP connected. I have lots of Cisco VOIP-compatible equipment laying around I can use, so one of my idea’s was to use a Cisco 3845 to handle the connections to the PSTN and Asterisk server(s) to do the actual conference bridging and Sip connectivity.

I should note that I have 7+ years experience with Cisco, Nortel, Mitel, and Asterisk old-style PBX’s and VOIP systems so I have at least some idea of the complexity and work involved.

Here are the requirements generally:

  • This system would be totally separate from the main phone system and would do nothing but conference bridging. ie no Voice Mail, no DID, no internal calling, nothin but conference bridging!
  • 350 total simultaneous users
  • a maximum of at least 16 and preferably 32 users per conference call
  • If multiple servers are required to support the load, prefer they be a cluster or at least able to be managed together
  • Fancy extra features not required, as long as there is a host code and a participant code and a decent way to schedule and setup conferences, any other features are gravy
  • PSTN connectivity (up to 15 ISDN PRI’s) can be supplied by Cisco routers or the main corporate PBX (Nortel CS1000E)
  • I have access to high-end servers (dual multicore 3GHZ+ Processors and 4Gb+) of RAM
  • Would probably start with a 1 or 2 PRI proof-of-concept that could be used to test, refine, document, and then be expanded to full size

So, if anyone can answer the following questions that would be great:

  • What would be the general sizing requirements or setup required to use Asterisk to meet the requirements?
  • Has anyone done this before and if so, how many ports were involved and how has it worked out
  • Does the idea of doing this make experienced people go feral, ie does this sound like a REALLY bad idea
  • Other then Fonality, are there other vendors who could support such an environment. Recommendations good and bad greatly appreciated but no vendors sales guys please!
  • Any other comments on the requirements or other aspects that might represent gotchas

Thanks in advance
Nathan Spitzer

We had tried to test the conference capablity of asterisk. but it is only 16 parties at g.729 codec. I wish somebody can tell me the better clues.

So my solution to conference right now is using asterisk+ zhou500 conference bridge. the asterisk can support more than 500 simultaneous calls. but the conference voice mixture is a hard task, I’d like to use dsp hardware to do it.