"Open Source Voice over IP is ready for its close up. Asterisk, a popular Voice over IP PBX, has released version 1.0.0.
"Asterisk is a software Private Branch exchange (PBX) that also acts as an IVR platform as well as handling a myriad of other telephony related functionality. It is an open source project and licensed under the General Public License.
"Features include support for caller ID services, three-way calling, Voicemail services with Directory, call queuing and call conferencing..."