While Asterisk IP PBX software can be a boon for cash-strapped businesses that need phone upgrades, the free, open source platform has also spawned a host of for-profit vendors that charge for Asterisk professional services, peripherals and software extensions, and still manage to undercut the prices charged by more established IP PBX vendors.

Digium, the business founded by Asterisk creator Mark Spencer to capitalise on his PBX, says it plans later this year to release a new version that will support much larger deployments. New Jersey-based service provider VoicePulse plans a hosted PBX service based on Asterisk deployed on virtual servers.

With successful partnerships already under its belt, the company promises to broaden its influence this year as 3Com makes Asterisk available on a blade for its multifunction branch-office routers. This is in addition to the relabelled commercial Asterisk appliance made by Digium for 3Com small-business customers.

In Japan, NTT Software, a subsidiary of the country's biggest phone company, is preparing PBX appliances of its own that are based on Asterisk.

On a smaller scale, a growing group of start-ups lies at the heart of an Asterisk-based business community that has sprung up to exploit the basic platform. For instance, vendors Escaux and Fonality, to name two, sell full-blown custom Asterisk PBXs. Critical Links' Edgebox surrounds Asterisk with a router, Wi-Fi access point, NAC and other security to fashion a branch-office-in-a-box device.

Even an Asterisk online superstore called The VoIP Connection has sprung up to sell Asterisk appliances as well as phones, headsets, gateways and other add-ons needed to set up Asterisk networks.

It may not be right for every business, particularly the largest, but some vendors claim their Asterisk-based gear and services can cost one-tenth as much as equipment sold by major vendors such as Avaya, Cisco, Nortel, NEC and Siemens.

Despite its impressive array of partners, Asterisk is still a minor player in the PBX world, says Matthias Machowinski, an analyst for Infonetics Research.

In research his firm did a year ago in which 240 businesses were interviewed, just two said they used Asterisk-based gear, he says. "I would think it's a small part of the market," he says.

Since these companies are private, there are no numbers on how well Asterisk-based products sell, he says, but, "I'm sure it's pretty low at this point." IP PBX sales worldwide were estimated at $8.5 billion last year, $2.8 billion of that in North America, Machowinski says.

Still, there are signs that Asterisk is at least intriguing to a great number of people. Digium boasted at the end of last year that 1 million copies of Asterisk had been downloaded, indicating a very broad interest even if it is just from tyre-kickers.

Things to look for

For those who persevere and actually deploy Asterisk-based systems, the financial benefits can be huge. For instance, the City of Madera, in California, saved hundreds of thousand of dollars using free Asterisk IP PBX software to overhaul its phone system, but it had a knowledgeable network manager who could do all the work himself.

The city budgeted $400,000 that it fully expected to pay if it put out an RFP to major vendors. It wound up spending just $140,000 by using Asterisk, and that included a general network upgrade enabled by other open source software, says Paul Wheeler, the network manager who oversaw the project. The three redundant Asterisk PBXs in the network cost just the price of standard Intel servers, T-1 cards plus some of Wheeler's time.