FusionPBX

FusionPBX is an open source project that provides a customizable and flexible web interface to the very powerful and highly scalable multi-platform voice switch called FreeSWITCH. It can be run on the operating system you are comfortable with and hardware of your choice. Unlimited extensions, voicemail-to-email, music on hold, call parking, 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.