Sipfoundry released v 2.62 of its SipX, an open source enterprise PBX system which has features such as voice mail and auto-attendant. It can also be used as a high performance enterprise toll-bypass SIP router. It combines all common calling features, XML-based SIP call routing, Web-based configuration, and integrated management and configuration of the PBX and attached phones and gateways. It is a modular server-based solution that does not require any additional hardware, as it interoperates with any SIP compliant gateway, phone, or application. The changes in release 2.6.2 fix the numerous stability related problems found in 2.6.1. In addition, new software is more user friendly and interoperable with other systems. More information at SIPfoundry (News via Martin)
With Asterisk, SER, and SipX you’ve got a variety of open source VOIP tools that run under Linux. Each has their own strengths. The competition between them will spur improvements in all of them. It’ll be great.