PLEASE VISIT http://www.freeswitch.org for more up to date info.

What is it?

FreeSWITCH™ is an open source communications platform. FreeSWITCH™ is a library which ships with a small executable that loads the library, launches the core, and performs the various tasks that are defined by the modules. In its base form FreeSWITCH™ is a soft-switch or PBX telephony application, not completely unlike Asterisk but capable of handling thousands of simultaneous calls.

FreeSWITCH™ makes it possible to build a softphone, PBX system, soft-switch, or interface with other open source PBX systems such as OpenPBX.org, Bayonne, YATE or Asterisk. It can also be used to build a voip switching platform uniting various technologies such as SIP (using the Nokia Sofia library), H.323, IAX2, LDAP, Zeroconf, XMPP / Jingle etc.

As a library FreeSWITCH™ can be used by developers to enable switching in their custom applications. FreeSWITCH™ can be launched not only from a C application, but also via PHP, Perl, or a variety of other languages.

FreeSWITCH™ is written in C, built from the ground up (not a fork of another code base). It is designed to take advantage of as many existing software libraries as possible. It has a modular, extensible architecture, with few and necessary functionality in core ([libfreeswitch]]) with optional modules to do the rest.

FreeSWITCH runs on Windows, Mac OSX, Linux, *BSD, and other Unix flavours.

It is licensed under the MPL.