UK telephone code misconceptions

Widespread UK telephone code misconceptions, in particular brought on by the Big Number Change in 2000, have been reported by regulator Ofcom since publication of a report it commissioned in 2004.

The telephone area code for most of Greater London and some surrounding areas is 020, not "0207", "0208" or "0203". All London telephone numbers have eight digits, customarily written as two sets of four, originally a dialling code followed by a 4-digit local number. The London number (020) 7946 0234 can be dialled as 7946 0234 from any other land-line whose area code is also 020. A study was commissioned in 2005 which found that only 13% of respondents correctly identified the 020 code for London without prompting: 59% incorrectly identified it as "0207" or "0208". This is not just an issue of number appearance; the way that should be standard of calling a London (say) landline from within the London telephone area is to dial the last 8 digits, although the trunk prefix "0", and the area dialling code "20", if included, are ignored.

Other area codes with similarly widespread misconceptions about the correct area code include Bristol, Cardiff, Coventry, Leeds, Leicester, Northern Ireland, Nottingham, Portsmouth, Reading, Sheffield and Southampton.

Owing to the marked increase in demand for telephone numbers to be available for allocation since the 1990s, the United Kingdom's telephone numbering system has been restructured several times on both a national and regional level, resulting in several modifications to the way British telephone numbers are written. As a consequence of these changes, many people were left with a misunderstanding of how the system of area codes and local numbers operates.

A standard United Kingdom fixed telephone number (i.e. a landline, or geographical number, as opposed to a mobile telephone number or special rate non-geographic fixed line) is divided into three parts, the trunk prefix code (0 in the UK), an STD code (area code) followed by a local number. The STD (Subscriber Trunk Dialling) code indicates the geographical area of the number, and is dialled before the local number. For the majority of calls dialled within the same area, the trunk prefix and area code need not be dialled, but are ignored if so. Due to number capacity constraints, fixed line callers in Bournemouth, Poole and Christchurch (01202) must dial the full STD code even when calling local numbers. From October 2014, similar schemes were implemented in Aberdeen (01224), Bradford (01274), Brighton (01273), Middlesbrough (01642) and Milton Keynes (01908). Some telephone service providers differentiate ordinary calling costs using the relevant area code(s).

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