open-source pbxs make noise in voip

JUST AS LINUX,THE OPEN-SOURCE OPERATING SYSTEM, HAS GROWN from a geek Saturday night entertainment to the dominant industrial computing platform, software IP PBXs may be the next open-source giant on the horizon.

The open-source Asterisk IP PBX, the secret sauce powering several IP voice services, has moved beyond the exclusive club of telecom engineers and tinkerers who drove its early development. Today, Internet telephony service providers, resellers and integrators, as well as corporate IT departments, are adopting the technology to launch business and consumer services, or enterprise phone systems.

Open-source IP PBXs, such as Asterisk, created by a young technology firm, Digium, enable anyone with basic knowledge of computing and IP networking to set up their own phone system with advanced PBX features, a possibility that might send shivers down the backs of commercial telephone service providers.

Open-source software is usually available for free download from a sponsoring organization or company. Users are free to alter or add to the software as they choose, but, usually, those additions must be made available freely to others using the software. Software firms are free to offer commercial “distributions” of open-source software, such as Red Hat Inc.’s Linux, which typically includes support and authoring tools.

Asterisk is not alone in the open-source world. Pingtel Corp., the earliest vendor of IP phones, also developed SIPxchange, a software IP PBX system that it now promotes as an open-source product. The company offers an enterprise distribution of SIPxchange using a yearly subscription model that includes support and documentation of all the changes and additions to the product. And Asteria Solutions Group Inc., a developer of Asterisk systems for business, will ship a completely configured Asterisk IP PBX (on a PC) for 20 phones for $2,400. Some systems are as little as $400.

The VoIP Connection Inc., a typical vendor of configured Asterisk systems as well as hardware and software components, based in Florida, says its customers are residential and business Internet telephony service providers, many outside the United States, as well as small businesses.

“We just shipped a bunch of stuff to Kabul [Afghanistan],” says Mike Crown, managing partner, VoIP Connection. “We sell to Asia, the Middle East, Africa [and] Central America.” He adds that Asterisk has a lot of appeal in developing countries, “not just because of the price, but for the control. Nothing works all the time, but at least with open-source stuff you have a chance to make it work yourself. But with proprietary equipment, if it doesn’t do what you want, you’re pretty much out of luck.”

VoIP Connection offers a high-availability Asterisk box that is like a PC but has no moving parts: all memory is solid-state (no hard drive) and heat is dissipated with a heat sink. The $1,500 box includes a fully featured distribution of Asterisk sufficient for businesses or service providers. VoIP Connection augments its systems with a selection of IP phones, Asterisk software and powered Ethernet equipment (so phones stay up even if power goes out).

The business customers “have in-house IT staff and the ambition to set up their own system,” says Crown. “More and more, business IT is being charged with taking care of the phone system. They are migrating to platforms that they are more comfortable with, which is Linux on a PC-type platform and networking gear based on [Ethernet] standards that they are familiar with.”

Asterisk has been deployed much closer to home, with VoIP service provider VoicePulse building both its consumer service and more complex small-business services based on Asterisk.

Almost all of the open-source VoIP software products are built to run on the Linux operating system. And, all are generally supportive of industry standards, such as SIP for signaling.

Although the open-source software is available for free download, Asterisk is primarily the creation of Digium, based in Huntsville, Ala. Digium showed up at the recent Fall 2004 Voice on the Net conference in Boston, Mass., with a host of new products in support of Asterisk. These included server and client software; developers’ kits; a line of interface cards to traditional telephony equipment, such as channel banks and T1 lines; and an impressive selection of Asterisk T-shirts.

Mark Spencer, president of Digium, says for the new user, the company’s products offer “lots of features out-of-the-box, but it is in Linux and scriptable. They can do a complete implementation with the basic commands included in Asterisk. And, they can use the AGI (Asterix Gateway Interface) to script features.” He adds, “We are trying to be as abstract as possible so they can reuse scripts for different protocols, such as SIP or TDM or H.323.”

Although Asterisk has its own signaling system, IX, it also can work comfortably with SIP products, especially SIP phones and within SIP networks.

Digium constantly develops the open-source software. Issues are submitted to a “bug tracker” on staff. The problem is tested, and a patch is created. “If it is accepted, we then stick it into a development version of protocol. We have a development version and a stable version,” says Spencer.

Digium has seen burgeoning interest in Asterisk in the last year. In September, the company held a users’ conference in Atlanta, where it had reserved space for about 100 participants, but 500 showed up. Next time, Digium is looking for a venue that can accommodate more than 1,000 participants.