3CX and Appia present a complete VoIP PBX solution to all 3CX Phone System customers after interoperability testing proves successful. London, UK and Traverse City, Michigan, USA – 24 April 2012 – 3CX, developer of the popular Windows-based VoIP PBX, 3CX Phone System, has announced that integration testing with Appia Communications, a leading VoIP provider in…