Open-Source PBX Battle Brewing

In the open source PBX world, Asterisk is king, but it’s no longer the only game in town. The recent release of SIPfoundry's sipX, a freely available Linux-based PBX based on software developed by Pingtel, has added a bit of competition to the mix.

In the open source PBX world, Asterisk is king, but it’s no longer the only game in town.

SIPfoundry, a Westborough, MA-based group formed in March 2004 to promote open-source telephony applications based on the Session Initiated Protocol (SIP), has released a complete SIP PBX, called sipX, based largely on code contributed by IP telephony vendor Pingtel.

And though Digium, the company responsible for developing the popular Asterisk PBX, has enjoyed a virtual free ride in the world of open source telephony since Asterisk was made public in 1999, CEO Mark Spencer is welcoming the competition.

“It’s beneficial to have several companies offering open source systems,” said Spencer. “It validates the concept.”

Both Asterisk and sipX are written for the Linux operating system, but there are significant architectural differences between the two.

Asterisk’s architecture is designed around a core PBX engine, with applications layered on top to support a number of different protocols — including SIP, H.323, MGCP, IAX (itself an open-source protocol written by Digium), and potentially other yet-undeveloped protocols.

This approach, says Spencer, “offers significant benefits” for organizations that want to “support a heterogeneous network out of the box. ”

sipX is built from the ground up using 100-percent SIP-compliant blocks. Unlike Asterisk, sipX speaks SIP and only SIP, the protocol which has become the de facto industry standard and is credited for providing the basic foundation upon which much of the VoIP industry now sits.

By relying on SIP, says Pingtel CEO William Rich, sipX “provides a very high level of interoperability and scalability.”

The architecture of sipX, says Rich, allows systems developers to perform different functions on different servers, replacing the included components with custom-developed ones, or combining them in different ways.

“It allows organizations to freely choose hardware and applications best suited to their needs,” said Rich.

Another key difference between the two PBXes is the approach taken to the user interface: sipX has one while Asterisk, depending on your point of view, has either many or none.

Right out of the box, sipX’s basic functions are managed, for the most part, using a Web browser interface.

Digium has not released a unified management tool for Asterisk, requiring users to learn complex text-file or command-line based configurations. Though there have been a number of “after-market” GUI-based interfaces for Asterisk released by independent developers, none is credited for making the PBX easier to implement.

One similarity between the two open-source PBXes is how the companies behind them hinge their respective business models on their open source offerings. Each hopes acceptance of their free software packages leads to sales of their commercial products.

For Digium, that product line has been a range of hardware add-ons for PCs running Asterisk, though, recently, Digium also began offering installation and technical services for a fee.

Pingtel, last year, went though a dramatic transformation from a primarily hardware-based to an exclusively software-based telephony company when it sold its hardware line, including its space-age designed Xpressa IP phone, to an undisclosed buyer.

Today, the company’s product line consists of a softphone and high-end commercial PBX implementations, such as the company’s SIPxchange PBX, a commercial distribution targeted specifically at the enterprise market. Pingtel officials compare their open source/commercial approach to that adopted by Linux distribution powerhouse Red Hat, which has made its open-source Fedora distribution of Linux freely available while selling a significantly enhanced distribution called Red Hat Enterprise.

Rich is convinced that this dual approach both makes business sense and benefits users.

“This changes the fundamental economics of the PBX business and shifts the balance of power to customers,” says Rich. “This shift will absolutely cause prices to go down” as proprietary products become commodities and new competitors take market share.