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Demand for IP telephony based on open source software will generate more business over the next few years than the entire Linux marketplace, predicts Jon “Maddog” Hall, president of Linux International.

Mr Hall believes the main driver will be open source private branch exchanges, such as Asterisk and sipX, which offer sophisticated enterprise phone systems at a fraction of the cost of proprietary systems.

Proponents cite the usual benefits: cheaper technology and stronger code. But in the case of IP-based PBXs, also known as communications servers, the price advantage can be huge.

Consider so-called “meet me” conferencing, where a user sets up a multimedia session. “Cisco charges an extra $75,000 to do that. But that’s a standard feature on our communications server, which costs about half their basic platform,” says William Boehlke, chief executive of Signate, which sells an IP PBX.

Today, open source PBX users tend to be smaller, technology-savvy companies and government offices. But larger companies are also interested. Pingtel, which markets a business class version of sipX, says it will shortly announce a deployment of up to 10,000 seats for a US retailer.

But adoption “will reach a tipping point in nine to 12 months” and open source will begin to have a “huge impact” on the PBX market, says Martin Creaner, chief technical officer of the TeleManagement Forum, a telecoms industry group.

So far, the big vendors are not concerned. “We don’t see open source PBXs as a threat,” says Henri Tallon, responsible for global IP PBX marketing at Nortel. “They have limited feature sets and the workload required for customisation and integration can be onerous.”

Open source developers often just want to improve a technology rather than create an alternative commercial product, he adds.

“Open source thrives among technically-savvy users, and struggles to move beyond that until a platform matures and a good business model is wrapped around it,” says Mark Seery, research director at analyst house Ovum-RHK.

One problem to overcome is the complexity of installing systems. “Mom and pop shops are not going to learn Linux to install a phone system,” says Mark Spencer, creator of Asterisk.”

Mr Spencer pioneered the open source PBX when he built Asterisk as a phone system for his start-up company. Seeing an opportunity, he made the source code freely available and refocused his business, renamed Digium, on commercialising the PBX.

Today, Digium sells phone system components and lets other companies package them for end users.

Although many Asterisk deployments are self-catering affairs, larger enterprises and even communications service providers are also relying on it. BT uses Asterisk internally and Vonage is rumoured to run a commercial service on it.

Its potential is also being recognised by IBM and Intel, which are working on ways to beef up Asterisk for more demanding applications.

But Asterisk faces com-petition from sipX, created by the SIPfoundry developer community. Much like Asterisk, the sipX code is commercialised by Pingtel, which was the primary developer of sipX.

“We take the open source code, put quality around that and package it as binary that customers can use,” says Bill Rich, chief executive of Pingtel and a founder of SIPfoundry.

Observers say that sipX lacks the feature-richness of Asterisk, although the gap will close as the SIPfoundry community grows.

Today, SIPfoundry has 3,000 members and reports 6,000 downloads of sipX a month. Digium claims “hundreds of thousands” of Asterisk users and counts 250,000 downloads from its site in the past eight months.

A point in favour of sipX’s development is that it is built purely on open source SIP code, whereas Asterisk partially uses a proprietary protocol copyrighted by Digium. The challenge for Asterisk is code stability. By having an old-fashioned coding style, the code becomes what software engineers call “spaghetti”.

It is only a matter of time until a virus brings down Asterisk servers,” says Dr Christian Stredicke, chief executive of Snom Technology, a German VoIP vendor. “Examples like SIPfoundry show the true open source community can do better.”

Copyright The Financial Times Limited 2019. All rights reserved.

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