Private branch exchange (PBX) business phone

A private branch exchange (PBX) system, often referred to interchangeably as private automatic branch exchanges (PABX), is an automatic telephone switching system that enables users within an organization to place calls to each other without having to access a public switched telephone network (PSTN). A PBX system generally provides telephone usage information such as call start time, call duration, and call charge when an extension subscriber communicates with an external subscriber through an office line. In a basic PBX system, the PBX is connected between the central office switch and the individual telephone stations. In a computer/telephony integration a computer is connected to one of the station lines to emulate the telephone terminals with the end result of controlling most of the features offered by the PBX through the computer interface. A PBX typically includes a private switch, usually on the enterprise's premises, connected to a common group of lines or trunk circuits running from one or more central offices to provide communications service to a number of individual phones. A private branch exchange system can be provided on the premises of a public office, hospital, or company to make a connection between a central office (CO) line and extension subscriber or between extension subscribers. Typically, a PBX environment uses digital telephone terminals and digital switching. Digital PBX switches were designed to handle analog voice traffic, with the switch performing an analog-to-digital conversion (DAC) so that digital switching can be used internally on the entity premises. Increasingly, however, private branch exchanges are carrying data traffic as well as voice traffic.