FreePBX is a web-based open-source graphical user interface (GUI) that manages Asterisk, a voice over IP (VoIP) and telephony server.

[5] FreePBX was initially released as the Asterisk Management Portal (AMP), version 1.10.002.

This was originally created by Coalescent Systems and was a simple database that wrote configuration files for Asterisk to use.

Updates have included new modules and support for additional capabilities such as voicemail, calling queues, fax, multiple languages, DAHDI and a local user directory.

[33] FreePBX developers estimate the distro has been deployed in millions of active PBX systems in over 220 countries and territories.

[34] When Digium took over the Asterisk project, they released a series of SIP phones that tightly integrate with FreePBX, including provisioning support and apps.