A business/traditional telephone system is any of a range of a multiline telephone systems typically used in business environments, encompassing systems ranging from small key systems to large scale private branch. A business telephone system differs from simply using a telephone with multiple lines in that the lines used are accessible from multiple telephones, or “stations” in the system, and that such a system often provides additional features related to call handling. Business telephone systems are often broadly classified into “key systems”, “hybrid systems”, and “private branch exchanges”.

A key system was originally distinguished from a private branch exchange (PBX) in that it allowed the station user to see and control the calls directly, manually, using lighted line buttons, while a private branch exchange operated in a manner similar to the public telephone system, in that the calls were routed to the correct destination by being dialed directly. Technologically, private branch exchanges share lineage with central office telephone systems, and in larger or more complex systems, may rival a central office in capacity and features.

There is a time and place for traditional phone systems (PBX Systems). In cases where up-time is a necessity, these systems are often used. Traditional phone systems are more costly and complex to setup than a VOIP/IP system due to all the components and maintenance required.

System components

A PBX often includes:

  • The PBX’s internal switching network.
  • Microcontroller or microcomputer for arbitrary data processing, control and logic.
  • Logic cards, switching and control cards, power cards and related devices that facilitate PBX operation.
  • Stations or telephone sets, sometimes called lines.
  • Outside telco trunks/lines that deliver signals to (and carry them from) the PBX.
  • Console or switchboard allows the operator to control incoming calls.
  • Uninterruptible power supply (UPS) consisting of sensors, power switches and batteries.
  • Interconnecting wiring.
  • Cabinets, closets, vaults and other housings.