3CX Phone System is an IP based PBX system that can totally replace a proprietary hardware PBX. It supports standard SIP soft/hard phones and can lower call costs via VOIP service providers while still supporting traditional PSTN (Public switched telephone network) phone lines. The software provides a web based configuration interface.

Evolve your communications with 3CX Phone System for Windows - an IP Phone System that totally replaces your proprietary PBX, supports standard SIP soft/hard phones, VOIP services and traditional PSTN phone lines. 3CX Phone System is far less expensive than a traditional PBX and can reduce call costs substantially by using a VOIP service provider. Its web-based administration makes phone system management easy. 3CX Phone System eliminates the phone wiring network and allows users to hot desk simply by taking their phone. Key Features:
* Complete phone system - Provides call switching, routing & queueing
* Purchase cost dramatically lower than a traditional hardware PBX
* Scaleable - Unlimited extensions and phone lines. No proprietary expansion modules needed!
* Web based configuration & status indication - Easy phone system management!
* Unified messaging - Receive voice mail via e-mail
* Auto attendant (e.g. 1 for sales, 2 for support, etc.)
* Reduce long distance and inter office call costs
* No more expensive proprietary system phones - Use standard SIP phones
* Eliminate the phone wiring and make moving offices easier
* Configuration "out of the box" for many VOIP providers

The license of this software is Freeware, you can free download and free use this phone software.