Understanding Asterisk

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Aug. 03, 2005 09:11 AM

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URL: http://conferences.oreillynet.com/cs/os2005/view/e_sess/6989...

Imagine having a burglar alarm that could detect motion in your living room, then immediately call you, a nearby family member, or trusted family friends who could investigate -- in that order, the first person who might answer the phone.

Maybe that doesn't sound very impressive, but consider that you can build this system for the price of a webcam, a telephony card, and a little bit of work setting up and configuring Asterisk. It's even more impressive if you can
plug a phone into your laptop in a hotel conference room, flip on a light in your living room remotely with X10, and receive the phone call even before the web browser updates the view from the web cam.

That's what Brian Capouch did in his Tuesday afternoon OSCON 2005 tutorial on understanding Asterisk. This impressively large and featureful piece of software is the brains of a telephone system. There are a lot of terms and
ideas to learn, but if you have some experience with telephony (or are willing to learn), the software is stable and sensible.

Though there are a lot of boring applications (if replacing hundreds of thousands of dollars of proprietary PBX devices and software with a commodity PC and open source software is boring), there are a lot of cool ideas
too -- building a custom voice mail system, having nearly unlimited extensions, having phones that don't care where you are in the world, but always ring if you have an IP connection. My brother wants to put a soft phone in his son's room and another in our parents' house, so that Jacob has a direct line to Grammy and Grampy.

If you've done telephony before, you know that the fairly useless telephone companies have predatory pricing. You do have to spend a bit of money for hardware (unless you use software phones and pay someone else for access to
the standard boring telephone system), but Capouch revealed that the newer Linksys WR54GS wireless devices (and especially the NetGear versions) run Asterisk nicely. Adding a small USB device and upgrading the antenna or the
wireless card can give you up to ten miles of wireless-enabled calling -- perhaps for $250.

Installation and configuration are still more involved than the average phone user might want, but complication has a way of vanishing as new contributors and businesses start to expand their audiences. It's hard to imagine how the
current system will last, in the face of convenience, cost, and customizability. VoIP is coming.

chromatic manages Onyx Neon Press, an independent publisher.