All-figure dialling refers to the change in the UK telephone numbering plan in 1966 when the three-digit numbers for local telephone exchanges in director areas (major metropolitan areas) began to be assigned without reference to any correspondence to the letters on the telephone dial. The six areas (cities) were: Birmingham, Edinburgh, Glasgow, Liverpool, London, and Manchester.
Similar changes have taken place in the numbering plans of other countries where letters were used on the dial.
Prior to the introduction of all-figure dialling, local exchange numbers in director areas were assigned to correspond to the name of the exchange, i.e for a number in the Wimbledon exchange, "WIM 1234" which translates to 946 1234. Due to the introduction of international direct dialling where different countries' telephone dials differed, this system became unworkable and all figure dialling was introduced.
Note that the correspondence of letters to numbers in UK telephone numbering plan differs from that used in North America, as well as from that used on modern GSM phones; see Rotary dial.