Jitsi (previously SIP Communicator) is an audio/video and chat communicator that supports protocols such as SIP...
IMCapture for Skype (was SkypeCap) captures and records audio and video calls made from Skype.
It helps you initiate calls, send text, start a conference, or send faxes.
XiVO Client is an application that connects you to the XiVO server.
Free-to-use VOIP software for Mac OS.