Subscriber trunk dialling. The scheme for full automation of the telephone service in the United Kingdom

Plans have been prepared by the Post Office to enable subscribers to dial their own trunk calls. This is called `subscriber trunk dialling¿ (s.t.d.). The new service will be opened at Bristol Central Exchange in December, 1958, and will be extended as rapidly as resources permit. By the end of 1961, subscriber trunk dialling is expected to be available in over 100 centres. A national numbering scheme has been prepared, and ultimately a long-distance call from any part of the United Kingdom will be obtained by dialling the national number of the required subscriber. Local numbers will be unaffected. Exchanges have been divided into groups for charging and routing purposes. The charging and routing will be controlled by register-translator equipment (Grace), an electronic form of which will be used for the larger installations. In s.t.d. areas, new methods of charging for calls will be introduced. All calls will be timed, and the unit fee will be reduced to 2d. The existing 3 min minimum charge will not apply to s.t.d. calls. Instead, unit fees will be recorded, each unit paying for a period of time which depends on the distance of the call. Both trunk and local units will be registered on existing subscribers´ meters, and a bulked bill will be rendered. Private meters will be rented to subscribers who require them. Accounts will be sent to s.t.d. subscribers quarterly, and the preparation of accounts will be increasingly mechanized. A new coin box has been developed so that trunk calls in s.t.d. areas can also be dialled by coin-box users.