TeamTalk 5

 TeamTalk is a feature-rich conferencing application aimed at providing everyone a VoIP solution regardless of connection speed. Includes video conferencing, desktop sharing, file sharing, audio streaming, recording, and much more. Audio push-to-talk and audio detection are both available. Features include quality controls, packetloss resistance, de-noising of outgoing audio, 3D positioning of sound, and much more.
Windows | Mac | Linux i386 | Linux x86_64 | Raspbian Raspberry Pi armhf | CentOS 7 x86_64 (server only)