System operation of a t.d.m. switched highways electronic telephone exchange

The Post Office and its principal telephone manufacturers have developed jointly an experimental electronic telephone exchange which will be installed at Highgate Wood Exchange in North London. The exchange is designed to operate on time-division-multiplex principles using switched highways, and these techniques are used throughout the common control apparatus. The paper describes the setting up of normal calls and their subsequent control, with particular reference to those parts of the exchange which fulfil the functions of providing speech connections between lines, detecting calling conditions, processing dialled information, selecting the called lines, controlling established connections and metering.