Free as in freedom, and free as in no cost, too!
GNU Call is a free and open source project that provide a secure and self organised VOIP (Voice over internet protocol) service to all user worldwide for private use and public administration.
It’s an perfect open source alternative for popular Skype VOIP service.
GNU Call use the open standard SIP protocol and GNU SIP Witch to create secure and self organised peer to peer mesh calling network so that the service will not rely on one single service provider.
It also work with your existing GNU SIP Witch, a server use for SIP calls which provides a method of managing and routing calls.
With GNU Call User can directly and secularly Call each other in full privacy without registering with any service provider.
The service still under development and planning to make it easy to use Internet telephony for real-time voice and video communication worldwide over the internet in fact for all forms of real-time collaboration for free.
Visit : GNU Free Call