There is a venerable PBX system available in Asterisk and its variants for *nix OS, this has even been ported to Windows and is called AsteriskWin32 that runs under CYGWIN.

If you are looking for a pure Windows native PBX system, that comes in freeware version is 3CX. There are plenty of Windows based high priced PBX software available on the market, not to mention, Cisco’s Call Manager. The freeware version and the cost of the paid version itself puts 3CX in a whole different category.

The 3CX system is in active development, supports almost any SIP device and will even connect to VOIP service providers along with connecting to PSTN via VOIP gateways. 3CX is not yet SIPConnect certified, for those of you who desire to connect it to PSTN without any interconnect but that functionality is being worked out as per their user forum.

The beauty of 3CX system is it comes with the PBX software and also a softphone that is easy to use and SIP based, call quality is just like a POTS line, no echo issues and configuration is simple.

The best feature of all…The management console is totally web based! Simply connect to the management console via any web browser and change any aspect of the 3CX configuration.