Asterisk

Asterisk  
Many companies and private residents alike are finding themselves in situations where they have an existing phone system that they'd like to continue using, but want to take part in the incredible savings & feature sets that VoIP technology offers. Normally, these people would be forced to replace their existing phone systems with new phones and other VoIP-compliant hardware that, although beneficial, can be costly for those who are unprepared to make that investment. Digium-Certified Asterisk Professionals can help solve this problem by providing an alternative, Asterisk, which allows users to bridge the gap between their existing systems and VoIP technology while spending a comparatively small amount.

Originally created by Mark Spencer of Digium, Inc., Asterisk is a complete PBX in software. Asterisk was developed to run on Linux, but is also capable of running on OSX and BSD systems. It can do VoIP in four different protocols, and can interoperate with nearly any piece of standards-based telephony equipment without using expensive hardware. Furthermore, Asterisk can be used with some of the most popular VoIP protocols (IAX, H.323, SIP, MGCP, and SCCP), and can work with traditional telephony elements as well.

Asterisk has support for one of the most expansive feature-sets found anywhere in the telephone industry, including, but not limited to, the features listed below: