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Open Source VoIP Guide Part 1: An overview

Adam Turner

Open source is claiming a seat at the table when it comes to Voice over IP - but is it open for business?

Firstly, the myth open that source software is "free" has long been dispelled. Sure you don't pay for the actual source code, but that doesn't mean you won't be out of pocket. As with any IT project, your significant costs include hardware, deployment, training and maintenance - regardless of the software behind the scenes.

Yet even when you take price out of the equation, open source is no longer purely in the domain of geeks. Open source has made significant inroads into the business world - led by projects such as the Apache web server and the Red Hat Linux operating system. The MySQL database, SugerCRM customer relationship management suite and Joomla! content management system are also open source success stories.

So what about open source and Voice over IP? There are a number of open source VoIP applications that turn a computer into an IP PABX - such as FreeSwitch, OpenSER and YATE - but by far the most widely deployed is Asterisk. The Asterisk platform was developed by Mark Spencer in 1999 while still a Computer Engineering student at university. When faced with the high cost of buying a PBX for his company, Linux Support Services, he simply wrote his own.

Today, Spencer is the chairman and chief technical officer of Alabama-based Digium, which sells hardware as well as Asterisk services and support. Spencer was recently named by

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Network World as one of the 50 Most Powerful People in Networking, next to Cisco's John Chambers, Microsoft's Bill Gates and Oracle's Larry Ellison.

Asterisk's strength is its flexibility, a product of the open source development model, Spencer says.

"It's a very pragmatic technology that is designed to try to talk to everything, to be architectured in virtually every way and be able to support as wide a number of applications as possible. That has been the key to its success, but that absolutely would never have happened if it hadn't had been for its open source nature," he says.

"As a company we can't focus on all the different markets, applications and technologies but, being open source, Asterisk can pursue all these directions because we have all these people who are taking it to all those places. Now we are really starting to see the benefits of that."

NEXT: What do users have to say about it?