Software per Call Center
Java VoIP Softphone (SIP) (replaced by jfPhone)
Accent interfaces and controls systems through goals and policies
Samples and wrappers around the Bria desktop API
Cress is a comprehensive toolset for graphical service/workflow design
JAvascript Voicexml InterpretER
The OZEKI VoIP Service Checker allows you to check VoIP services.
A suite of open-source tools and frameworks for creating SIP apps