Asterisk vs FreePBX
An open source telephony switching and private branch exchange service for Linux. Information on downloading, installation of and support for the product. Asterisk is like a box of Legos for people who want to create communications applications. It includes all the building blocks needed to create a PBX, an IVR system, a conference bridge and virtually any other communications app you can imagine.
FreePBX is a web-based open source GUI (graphical user interface) that controls and manages Asterisk (PBX), an open source communication server. FreePBX is licensed under the GNU General Public License (GPL), an open source license.