FreeSWITCH

FreeSWITCH™是一种开源运营商级电话平台，作为背对背用户代理实施。 由于这种设计，它可以执行从PBX到转接交换机，TTS（文本到语音）转换，音频和视频会议主机，甚至VoIP电话等的大量不同任务。（FreeSWITCH™ is an open source carrier-grade telephony platform implemented as a back-to-back user agent. Because of this design it can perform a great number of different tasks from a PBX to transit switch, TTS (text-to-speech) conversion, audio and video conferencing host, and even a VoIP telephone and more.）