PBX limiting exchange outgoing calls to authorised extensions - assigns special code to extensions and selectors sending abbreviated selection signals

摘要

The p.b.x. has selectors assigned to the exchange line repeaters. Each selector is engaged by a calling extension by dialling a given code. Circuitry determines the calling extension's authorisation and couples the repeaters to allow the selector either to send an abbreviated call number or to send prefixes describing an area of a direction. The code dialled for reaching a selector is not evaluated as part of a local call number.