Common control for an electronic private branch exchange
24 June 2013
IN THE BELL System's No. 101 Electronic Switching System (ESS), also known as the electronic private branch exchange (PBX), a single centrally located unit has been designed to control the operation of a maximum of 32 remotely located switch units.1,2 The control unit will be located at a central office, while the switch units each will be located in a different PBX customer's office. A particular switch unit may serve up to 200 lines, while the control unit may accommodate up to 3,200 lines.