Asterisk Telephone System

Asterisk® is the most popular and extensible open source telephone system in the world, offering flexibility, functionality and features not available in advanced, high-end (high-cost) proprietary business systems. Asterisk is a complete IP PBX (private branch exchange) for businesses, and can be downloaded for free. Asterisk® is released as open source under the GNU General Public License (GPL), meaning that it is available for download free of charge. Asterisk® is the most popular open source software available, with the Asterisk Community being the top influencer in VoIP.