Telephone numbers in the United Kingdom are administered by the UK government's Office of Communications (Ofcom). For this purpose Ofcom established a telephone numbering plan, known as the "National Telephone Numbering Plan", which is the system for assigning telephone numbers to subscriber stations. Since 28 April 2001, almost all geographic numbers and most non-geographic numbers have 9 or 10 national (significant) numbers after the "0" trunk code. All mobile telephone numbers have 10 national (significant) numbers after the "0" trunk code. The overall structure of the UK's National Numbering Plan is: A short sample of geographic numbers, set out in the officially approved (Ofcom) number groups: In the United Kingdom, area codes are two, three, four, or, rarely, five digits long (after the initial zero). Regions with shorter area codes, typically large cities, permit the allocation of more telephone numbers as the local number portion has more digits. Local customer numbers are four to eight figures long. The total number of digits is ten, but in a very few areas the total may be nine digits (after the initial zero). The "area code" is also referred to as an "STD (code)" (subscriber trunk dialling) or a "dialling code" in the UK.
Who is responsible for phone numbers in the UK? How is  the office's name abbreviated? What did they establish to assign numbers? What is the first digit in UK phone numbers? What's this called? How many digits follow it? How many for mobile phones? What is the overall structure of the plan? How long are area codes? Where are shorter ones usually found? What  do they have more of? How long are local customer numbers? How long is the total amount of digits? Is it ever different? What's another term for the area  code? Any others? What? Since what date has this system been in place?
the UK government's Office of Communications Ofcom the "National Telephone Numbering Plan", 0 a trunk code 9 or 10 (significant) numbers 10 A short sample of geographic numbers, set out in the officially approved (Ofcom) number groups from two to 5 digits large cities telephone numbers four to eight figures long generally ten Yes STD code Yes a "dialling code" 28 April 2001