As of July Avaya no longer participates in SIPFoundry. SIPFoundry has forked the code base and is being maintained by a new startup company. OpenSCS will have an initial release shortly as Avaya releases its SCS 4.0 release.
Note: The JIRA being used in SIPFoundry is no longer accurate as all the former contributors from Avaya aren't participating any longer.

Our effort to develop the sipXecs IP PBX started with our involvement with the Internet Engineering Task Force (IETF), the standards body that rules the Internet. Telecommunications was always something entirely different from data networking, until the Session Initiation Protocol (SIP) was invented. Like the invention of Hypertext Transfer Protocol (HTTP) fundamentally changed our lives, the SIP protocol holds the potential to change our lives again.

sipXecs is the largest open source effort around to build an IP PBX for unified communications using the Session Initiation Protocol (SIP). It is also the only solution that focused on ease of use from the beginning.  And we promise not to release software before it is tested. OpenSCS is a project run by Avaya, the copyright owner to the sipXecs codebase.

Nortel Acquired Pingtel August 2008			Avaya Acquired Nortel December 2009

sipXecs was a project started by Pingtel who were trying to form a new business model after trying to release SIP phones. Pingtel was acquired by Nortel in 2008 at which point sipXecs was on release 3.6. Nortel started a commercial offering (SCS) based on the sipXecs code which they purchased and owned copyright from Pingtel. Nortel had 3 major releases of SCS which correlate as follows:

After Nortel when into bankruptcy protection it was acquired by Avaya and SCS was chosen a go forward technology for the small medium enterprise in Avaya.

And here we are....