Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application.

Voxeet is VoIP web conferencing software that uses 3D high definition voice technology to produce immersive sound.

Google Voice is a telephony service that provides call forwarding and voicemail services, voice and text messaging, as well as U.S. and international call ter…