All-figure Dialling

The change to all-figure dialling occurred between 1966 and 1970 when letters ceased to be used in place of numbers to represent telephone exchanges in area codes. The transition was initiated by the General Post Office and was one of the first in a long series of changes in the organisation of telephone numbers in the United Kingdom. In most areas the change initially only affected the way area codes were presented, but in six multiple exchange director areas such as the London telephone area, the change coincided with the transition to new local exchange codes. The period of parallel running when both old and new codes were operational ended in 1970 with the ANN: All-figure Numbers Now advertising campaign. The changes were required for the continued good operation of the telephone service, but were considered controversial at the time. They occurred because of the increase in subscriber dialled international calls from countries which used a different allocation of letters to numbers on the rotary dial and because the number of useful exchange mnemonics that were possible under the existing system was being exhausted. The implementation of all-figure dialling and new local exchange codes in director areas allowed changes to be made to the way calls into and out of these areas were routed.