The keys to mainstream market success for many technological innovations — and often the most difficult ingredients for them to come by — are interoperability and openness. SIPfoundry has announced a Linux-based open PBX architecture and other advancements to help ensure that Session Initiation Protocol isn't slowed by such hurdles.

SIPfoundry, an industry consortium launched almost one year ago to promote SIP adoption, has released sipX, a binary version of a SIP PBX/proxy server that can be downloaded free from its Web site.

“If you want to build SIP into your product or network, this is something the industry can hone in on,” said William Rich, president and CEO of Pingtel, the company that might have been most instrumental in establishing SIPfoundry last March. “You can download individual pieces of the PBX or all of it. We hope that a key outgrowth of this will be more rapid adoption of SIP and less proprietary development by large vendors.”

PBX vendors might panic at the thought of someone offering free SIP PBX downloads, but Rich said SIPfoundry believes that those vendors still will be able to add their own features and competitive differentiation to products, while benefiting from the easy access to open standard building blocks.

“Having an open platform is one way to ensure that what the SIP spec says is what everyone builds,” said Robert Sparks, chief technology officer for Xten Networks, another SIPfoundry member.

The sipX PBX consists of a proxy server, a media server, a provisioning component and a softphone, all running on a Linux operating system.

In addition to the launch of sipX, SIPfoundry made two other announcements that could further SIP interoperability and market maturity. The group announced the latest version of its reSIProcate protocol stack, equipped with a dialog usage manager (DUM) that accelerates SIP development.

“The DUM layer has a call model capability, and it automates what had been a lot of manual actions,” Sparks said. “Previously, if you were building with SIP, you had to start from scratch by creating your own protocol stack. This is another thing that sets the stage for a proliferation of SIP-enabled devices.”

Rich said telcos have begun licensing the stack and may publicize that fact in the coming months.

SIPfoundry also announced the SIP Interoperability Project, based on the existing test framework developed by the SIP Forum. Rich described SIPfoundry as “a companion play” to the SIP Forum that goes beyond standard interpretation.

“The SIP Forum doesn't produce software or test programs,” he said. “SIPfoundry is a place where code is produced as an implementation of the standard.”