Social Source Commons

Free IP PBX / SIP server supports set-up of professional phone systems that allow you to create extensions, transfer calls, and extend VOIP services to all users. Works via your computer network (no separate phone wiring) and allows use of SIP software phones on your PC or any SIP hardware phone.

Offers virtual PBX, with good programming capabilities for each extension. Also supports virtual faxing and fax blasting. Generally integrates email with analog phone and fax communications.