Jitsi

Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application for Windows, Linux, Mac OS X and Android. It supports several popular instant-messaging and telephony protocols, including open recognised encryption protocols for chat (OTR) and voice/video/streaming and voice/video conferencing (SIP/RTP/SRTP/ZRTP), as well as built-in IPv6, NAT traversal and DNSSEC. Jitsi and its source code are released under the terms of the Apache Software Licence.

Jitsi

Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application for Windows, Linux, Mac OS X and Android. It supports several popular instant-messaging and telephony protocols, including open recognised encryption protocols for chat (OTR) and voice/video/streaming and voice/video conferencing (SIP/RTP/SRTP/ZRTP), as well as built-in IPv6, NAT traversal and DNSSEC. Jitsi and its source code are released under the terms of the Apache Software Licence.