In a IP-PBX telephone system implementation, a computer network is required by the telephone system. The telephone handsets plug in to that computer network, which may be either dedicated to the telephone system or shared between the telephone system and the data network that the computers connect to. The IP-PBX still connects to the Public Switched Telephone Network (“PSTN”) for outward calls.
An IP-PBX telephone system implementation provides a robust and reliable voice communications facility. Call quality is typically extremely good as it relies on the PSTN for outward calls. It also provides the ability to make tariff-free inter-office calls by configuring the IP-PBX at each office and utilising a wide area network.
If the computer network is shared between voice and data functions, there is potential for call quality to be degraded. If dedicated computer networks are implemented, much of the potential cost benefit of an IP-PBX may be lost