sipXecs

The sipXecs IP PBX is an open source alternative to commercial private branch exchange (PBX) systems from vendors such as Avaya, Nortel, Cisco, Siemens, NEC and others. Vis-a-vis Asterisk sipXecs scales to larger installations, offers more unified communications features and is easier to use. The sipXecs IP PBX is a native SIP based solution that offers all the typical features expected from a PBX, including voicemail, unified messaging, auto-attendant, conferencing, presence and call center capabilities. The sipXecs IP PBX can be deployed on a single server for smaller installations or as a distributed and optionally redundant system for larger deployments. It’s Web Services (SOA) based management and configuration system allows centralized management of a distributed system and offers plug & play configuration for all phones and gateways.

Homepage: http://www.sipfoundry.org/