Telephone Numbers in The United Kingdom - Overview

Overview

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.

The code allocated to the largest population is (020) for London. The code allocated to the largest area is (028) for all of Northern Ireland. The UK Numbering Plan also applies to three British Crown dependencies—Jersey, Guernsey and the Isle of Man—even though they are not part of the UK itself.

For dialling the United Kingdom from overseas, Ofcom and ITU-T recommendation E.123 states that numbers be written in the form:

It is common to see the form +44 (0)xxx xxx xxxx used instead (with an additional zero in brackets). This form is not recommended by Ofcom because it might confuse the reader. Callers within the United Kingdom substitute the +44 with the number zero (0). Calling +44 0xxx xxx xxxx will not work from most operators. It is therefore recommended to show the number in either the national or the international format, but not a mixture of both formats. The international format shows only those digits that overseas callers must dial.

Storing any UK telephone number in a mobile phone, or directly dialling it from the keypad, in the correct +44 international format (without the leading zero) allows the number to work when the mobile is calling out from any country of the world, including whilst still located within the UK. The "plus" sets the number type to international and so no International Access Code is required.