View source for FusionPBX:About

FusionPBX is an open source FreeSWITCH GUI. FusionPBX can be used as a high available single or multi-tenant PBX, call center server, fax server, voip server, voicemail server, conference server, voice application server, and a lot more. FreeSWITCHtm is a highly scalable, multi-threaded, multi-platform voice and pbx switch. FusionPBX license is the MPL 1.1 license.

It can be run on most operating systems on the hardware of your choice. It provides unlimited extensions, voicemail-to-email, music on hold, call parking, call center, call queues, analog lines or high density T1/E1 circuits and many other features. It provides the functionality your business needs and brings corporate level phone system features to small, medium and large businesses.