Discover the advantages of a software VoIP IP PBX3CX Phone System for Windows is a software-based IP PBX that replaces traditional proprietary hardware PBX / PABX. 3CX's 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 (software or hardware). A software-based IP PBX / PABX offers numerous benefits: