sipX ECS (Enterprise Communications Server) is an open source voice over IP-PBX platform best suited for large scale deployments.
In contrast to its main open source competitor Asterisk, sipX does not
play the role of a back-to-back user agent. This approach led to a modular and highly scalable system. All major components of sipX are implemented as servers and do not necessarily have to reside on a single
Eyepea and sipX
Eyepea selected sipX as its architecture makes it much more appropriate than Asterisk for large deployments where scalability and redundancy is key.
sipXecs is used by Eyepea as platform for large enterprises or for service providers.
Project site: www.sipfoundry.org