Building Your Own Conference Bridge

Written by lifang May 05, 2008 11:45

Conference calling is a poorly implemented feature on most telephone systems (do you even know how to set up a conference call on your PBX? if not, join the club). "Meet Me" conferencing systems and services make this much easier to do.In "Meet Me" conferences, you give participants a telephone number and extension to dial. This rings into a virtual conference room that allows up to several dozen people to participate in a two-way conversation. This is the easiest way to deal with conference calls because it is analogous to walking in or out of a real conference room. People simply call 800-nnn-xxxx extension xyz at the appointed time, and can come and go as they please.

The problem is that many telephone systems make setting a conference call up difficult at best. The conference host, or secretary, must often call out to people and manually add them to a conference. The results can be frustrating to say the least, especially if participants are on cellular phones.

However, if you conduct a lot of conference calls, the toll charges can add up, in which case you might want to buy your own conference bridge. Off the shelf conference bridges are expensive beasts, costing several hundred dollars to a thousand dollars per port (phone line). A system big enough to handle 100 callers can cost a pretty penny.

If you don't mind getting your hands dirty, you can build an El Cheapo conference bridge using the Asterisk open source PBX package combined with inexpensive telephone network interface cards from Digium (Asterisk's corporate sponsor). Asterisk supports meet me conferencing out of the box.

If your telephone system doesn't have built-in meet me conferencing, there are a couple of ways you can do this. One is to subscribe to outsourced conferencing services such as Webex, FreeConference.Com, and others (most long distance companies offer some type of teleconferencing service. There's no equipment to buy. You just tell participants what 800 number and extension to dial at an appointed time.

To configure this feature in Asterisk, edit the meetme.conf file to map one or more extension numbers to conference rooms (as shown in the example below, which creates three conference rooms numbered 9000, 9001 and 9002).