Asterisk (software)

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Asterisk logo.png
Developer(s) Digium
Initial release September 23, 2004 (2004-09-23)[1]
Stable release 20.5.2 / December 15, 2023; 2 months ago (2023-12-15)
Preview release none
Written in C
Operating system Cross-platform
Type Telephony software
License(s) GNU General Public License

Asterisk is a free open-source software implementation of a telephone private branch exchange (PBX). Like any PBX, it allows attached telephones to make calls to one another and to connect to other telephone services including the public switched telephone network (PSTN) and voice over Internet protocol (VoIP) services. Its name comes from the asterisk symbol, “*”. Asterisk is released under a dual license model, using the GNU General Public License (GPL) as a free software license and a proprietary software license to permit licensees to distribute proprietary, unpublished system components.

Originally designed for Linux, Asterisk also runs on a variety of different operating systems including NetBSD, OpenBSD, FreeBSD, Mac OS X, and Solaris. A port to Microsoft Windows exists as AsteriskWin32.[2] Asterisk is especially small enough to run in an embedded environment like customer-premises equipment-hardware running OpenWrt.[3]

Product history

Asterisk was created in 1999 by Mark Spencer of Digium. A public version 1.0 of Asterisk was released by Spencer while at Astericon on September 23, 2004.[1] Additional releases were:

  • 1.2 - Released on 15 November 2005[4]
  • 1.4 - Released on 26 December 2006[5]
  • 1.6 - Released on 2 October 2008[6]
  • 1.8 - Released on 21 October 2010[7]
  • 10.0 - Released on 15 December 2011[8]


Major features of Asterisk include[9]:

  • drivers for various VoIP protocols
  • drivers for PSTN interface cards and devices
  • call recording and monitoring
  • routing and call handling for incoming calls
  • outbound call generation and routing
  • media management functions
  • call detail recording
  • transcoding support
  • protocol conversion support
  • database integration
  • Web services integration
  • LDAP integration
  • single and multi-party call bridging
  • integrated "Dialplan" scripting language
  • external call management in any programming or scripting language
  • event notification and CTI integration
  • "text-to-speech" support
  • speech recognition

Hardware/software requirements

A C compiler and a variety of system libraries are required for a source-code-based installation of Asterisk. Please consult the Asterisk documentation.

For non-source-code-based installs (via AsteriskNOW or some other method), reference this section in the documentation.

Videos, screenshots, and other media

Introductory videos of Asterisk can be found on Digium's website.

Numerous videos of Asterisk in action can be found on gahlawat84's YouTube channel.

Additional videos demonstrating how to build VoIP clusters with Asterisk can be found on Telecom Channel's YouTube channel.

Entities using Asterisk

Further reading

External links


  1. 1.0 1.1 Keating, Tom (23 September 2004). "Asterisk 1.0 released". TMCnet. Retrieved 4 April 2012. 
  2. "Asterisk Win32 - The Open Source PBX for Windows". Retrieved 4 April 2012. 
  3. "Asterisk". OpenWrt. Retrieved 4 April 2012. 
  4. Keating, Tom (16 November 2005). "Asterisk 1.2 released". TMCnet. Retrieved 2009-03-26. 
  5. "Asterisk 1.4.0 released". 20 December 2006. Retrieved 2009-03-26. 
  6. "Asterisk 1.6.0 released". 2 October 2008. Retrieved 2009-03-26. 
  7. "Asterisk 1.8.0 Now Available!". 21 October 2010. Retrieved 2010-10-24. 
  8. "Asterisk 10.0.0 Is Released!". 15 December 2011. Retrieved 2011-12-26. 
  9. "About the Asterisk Project". Digium. Retrieved 4 April 2012.