Private branch exchange (PBX)

Private branch exchange (PBX) is an electronic switching device (or a special computer), located within the company, that automatically switches calls between the company’s telephone lines and those of a local telephone company.

It is a small telephone exchange that is owned by the organization, as opposed to the large public telephone exchanges owned by telephone companies.

A PBX performs a number of functions, such as call routing, call forwarding, redialing, storing, tracing the origins of calls for statistical purposes, and automatically determining the least expensive route for a long distance call. Networks that carry only voice and data from PBXs are referred to as PBX-based networks; those that integrate voice, data, and images are referred to as integrated services digital networks (ISDNs); they are covered below.