What Is Asterisk

by Brian McConnell
Asterisk is an open source PBX (private branch exchange) that provides all the functionality of high-end business telephone systems, and much more. It is the world's most flexible and extensible telephone system, providing many features that are not yet available in even the most advanced proprietary systems. It is also the world's cheapest telephone system. The software is free and runs on inexpensive Linux servers.

In This Article

  1. Asterisk's Feature Set
  2. What Can You Use Asterisk For?
  3. Where Can You Get It?

Asterisk's Feature Set

Asterisk was created by Mark Spencer of Digium (formerly Linux Support Services), and is now sponsored by Digium. Digium manufactures analog and digital telephone network interface cards that happen to work particularly well with Asterisk. This gives the company a long-term profit motive to support Asterisk, which is probably one of the main reasons the Asterisk project has succeeded where other open source telephony initiatives have failed to generate enough momentum to reach completion. Asterisk is currently in its 1.0 release, and sports a very impressive range of features for an early-stage product. Among the features baked into the system are:

  • Full support for analog, digital (T1, E1, PRI) and VoIP telephone interfaces (SIP, IAX and H.323 via external library)

  • Support for VoIP and analog telephone handsets

  • Ability to run in pure softswitch mode on generic Linux servers, Mac OS X and Windows (via CoLinux)

  • Ability to handle hundreds of concurrent calls on a single server

  • Extensive array of built-in call management features (e.g. call transfer, three-way calling, all of the usual bells and whistles found on business phone systems)

  • Voice mail with forwarding to internet email accounts

  • Meet Me dial-in conferencing

  • Fully configurable extension numbering (dial plan)

  • Automated call distribution (for customer contact centers)

  • Music on hold from a local recording or live MP3 or G.711 audio stream

  • Unlimited extensibility through AGI (Asterisk Gateway Interface), which allows developers to build custom CGI programs that control the telephone system (that is, interactive voice response systems)

  • Full LGPL source code

Asterisk: The Future of Telephony

Related Reading

Asterisk: The Future of Telephony
By Jared Smith, Jim Van Meggelen, Leif Madsen

Pages: 1, 2

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