Asterisk is a free, open-source toolkit for building PBX, VoIP, and telephony applications, maintained by Sangoma since its 1999 launch.
Researched and fact-checked by Bartu Cavusoglu · Updated July 18, 2026
Asterisk is an open-source framework for building PBX systems, VoIP gateways, and other telephony applications. Created in 1999 by Mark Spencer, it is now maintained by Sangoma Technologies, which also develops the FreePBX graphical interface commonly paired with it.
Running on standard server hardware, Asterisk handles call routing, IVR, voicemail, conferencing, and interconnection between the PSTN and VoIP networks.
Asterisk supports core PBX functionality, wide VoIP protocol coverage (including SIP and IAX2), IVR and call routing, conferencing, and voicemail/call recording.
It is extensible through a dialplan scripting language and APIs (AGI, AMI, ARI), letting developers integrate it with custom applications, call centers, and third-party systems.
Asterisk suits IT and telecom teams building custom PBX deployments, as well as VoIP service providers and developers building commercial calling platforms, provided they have the Linux and telephony expertise to configure and maintain a self-hosted system.
Yes, Asterisk is free and open source with no licensing cost.
Asterisk was created by Mark Spencer of Digium in 1999 and is now maintained by Sangoma Technologies.
No, Asterisk is configured via its dialplan and config files by default; most users pair it with FreePBX for a web-based GUI.
Asterisk supports SIP, IAX2, and other VoIP and traditional telephony protocols.