3CX Phone System for Windows is a software-based IP PBX that replaces a proprietary hardware PBX / PABX. 3CX IP PBX has been developed specifically for Microsoft Windows and is based on the SIP standard making it easier to manage and allowing you to use any SIP phone
Sangoma offer both the Sangoma FreePBX IP PBX and the Sangoma PBXcelerate PBX- Ready Appliances. Both built from the same proven, high-quality, industrial grade platform Sangoma products are known for
Digium Switchvox is an IP PBX based Unified Communications Business Phone System. Digium Switchvox is much more than just a business phone system and has VoIP and traditional calling, mobility, instant messaging, conferencing and much much more, all at an affordable price.
ZYCOO ZX IP PBX comes in number of models that are aimed at different sized industries from SOHO's to enterprise. The ZYCOO IP PBX range provide a variety of PBX features including voicemail and music on hold