sipXecs IP PBX (Enterprise Communications Server) is an open source software implementation of a Session Initiation Protocol (SIP) based unified communications system (IP PBX). Similar to a traditional private branch exchange (PBX), it allows a number of attached telephones to make calls to one another, and to connect to other telephone services including the PSTN and SIP Trunking services. sipXecs IP PBX is an open source alternative to commercial PBX offerings. It is easy to use and scales to several thousand users.
At one point, Open Hub analyzed source code for this project based on code location(s) available at that time. Since then, the code locations have been removed.