When Alexander Graham Bell created his first experimental telephone in 1875, it was unlikely he anticipated just how successful his invention would be. Even despite a recent decline in popularity due to the convenience of mobile phones, four in five UK households still have a landline installed in their home to plug a home telephone into.

Picking up the phone and calling someone is practically second nature to us. We are so used to being able to get through to someone quickly that it's hard to imagine a time when you had to speak to an operator to connect you to a local telephone number.

It was thanks to the introduction of Subscriber Trunk Dialling (STD) by the General Post Office in Bristol in 1958 that we are able to make calls without the need of a manual telephone exchange operator. Instead, the user calls another telephone directly using a specially assigned local or national dialling code. Part of the dialling code is known as an area code, and it identifies the area to which the telephone call is being directed.

In this article, we'll cover the history of area codes and how they have developed over the years as the telephone became increasingly more prominent in our lives. We'll also cover the more recent decision to switch to digital calling and what that means for landline users. So, let's get started!

An area code is the prefix of a telephone number that is assigned to a specific area or location. It is dialled to allow a user to connect automatically to another telephone without the need for an operator to manually connect the call from an exchange.

Area codes were introduced in 1958. This is the same year that Queen Elizabeth II made the first long-distance trunk call using the new Subscriber Trunk Dialling (STD) system. The call took place on 5 December from the Bristol Central Telephone Exchange and was received by Lord Provost in Edinburgh — the farthest distance a call could be made at the time. Not only did Queen Elizabeth make the first long-distance call on this day, but she also turned on the switch which connected 18,000 telephones to the Bristol Central Telephone Exchange, which revolutionised the automated telephone system in the UK.

To allow the system to be automated, callers used STD codes (now known as area codes) which are numbers allocated to an area of the country. From 1958 onwards, area codes were assigned to local areas, with the process completed in 1979, costing £35 million.

The origins of the area code go back to the 1920s when the General Post Office ran the telephone services, and adopted the Strowager system, allowing local calls to be automated. For London, however, the system was not sufficient to handle the number of calls, and so the Director telephone system was developed by the Automatic Telephone Manufacturing Company (ATM) to allow calls to be directed both automatically and manually in multi-exchange cities. The first Director system was introduced in the London Telephone Exchange in Holborne and then gradually introduced in Birmingham, Edinburgh, Glasgow, Liverpool, and Manchester.

Director Area Codes

As the calls using the Director system were automated, three-digit codes were assigned to each city's 'Director' to identify them in the telephone number. The three-digit number corresponded to the first letter of the city's name, except London, which was given the code '01'. The codes were as follows:

  • 01 London
  • 021 Birmingham
  • 031 Edinburgh
  • 041 Glasgow
  • 051 Liverpool
  • 061 Manchester

This code was then followed by a seven-digit number, of which the first three were represented by letters that identified the local telephone exchange:

  • 1
  • 2 ABC
  • 3 DEF
  • 4 GHI
  • 5 JKL
  • 6 MN
  • 7 PRS
  • 8 TUV
  • 9 WXY
  • 0 OQ

The last few digits of a phone number were specifically assigned to individual subscribers. For example, a subscriber in Wimbledon could be allocated the number WIMbledon 1234. To call that number, the caller would dial 01 for the London Exchange, followed by the numbers allocated to WIM, which are 946, and then 1234. This would mean the subscriber's telephone number in full is 01 946 1234.

Uniform Exchange Codes

Between 1958 and 1979, STD codes were allocated to each exchange in the country. The digits allocated to the local telephone exchanges are the ones that developed into the area codes currently in place today.

These used the same letter system that was in place when STD was first introduced in that they were based on the first two letters of the location of the exchange and the corresponding numbers on a telephone dial, and they always included a '0' at the front. For example, Aylesbury was assigned the STD code 0AY6, which means the A is counted as a 2 and Y is 9. As the telephone network grew and a number shortage developed, STD codes were converted to a format of (0XXX), and the local number was lengthened to a five or six-digit long code.

All Figure Numbering

Even despite this expansion, telephone numbers still ran out, and so All Figure Numbering (AFN) was introduced in 1966, starting with the Director areas previously mentioned. At this point, the use of letters for area codes was phased out in favour of numbering. Despite this, around 60% of current area codes still relate back to the alphabetic STD codes they once started as.

In addition to the abandonment of lettered area codes, in 1968, any number that started with '00' were changed. This freed up the '00' prefix, which was then used for premium-rate telephone numbers and as a short dialling code in the Republic of Ireland.

London Area Codes

In 1990, the area code for London (01) was replaced by 071 for Inner London and 081 for Outer London. This essentially doubles the available telephone numbers to 16 million. It also freed up the 01 area code, which was then allocated to all geographic area codes — this is a code allocated to a physical location with an allocated phone number.


On 16 April 1995, the digit '1' was inserted into each existing local number, hence the name. The international access code also changed from '010' to '00', which means that when callers ring an international subscriber, they dial '00' at the front of the telephone number.

Below are some examples of how UK geographic area codes changed as a result of 'PhONEday':

AreaNew numberingOld numbering
Ashford(01233) xxxxxx(0233) xxxxxx
Coventry(01203) xxxxxx(0203) xxxxxx
Birmingham(0121) xxx xxxx021-xxx xxxx
Cardiff(01222) xxxxxx(0222) xxxxxx
Edinburgh(0131) xxx xxxx031-xxx xxxx
Inner London(0171) xxx xxxx071-xxx xxxx
Outer London(0181) xxx xxxx081-xxx xxxx

The reason for this change was to use a prefix to identify the type of service that the user was calling. The prefixes are as follows:

Area code prefixService type
00International call prefix
0Standard Trunk prefix
01Geographic area codes
02New geographic area codes
03Originally reserved for new geographic area codes, but later used
for non-geographic number ranges but charged at geographic rates
05Corporate numbering
06Formerly reserved for future personal numbering
07Mobile phones, pagers and personal numbering
08Freephone and shared cost or special rates
09Premium rate numbers

Big Number Change

Due to the previous changes made on 'PhONEday', the '02' area code was free again and could be redistributed. This led to the 'Big Number Change' that happened in 2000. The Office of Telecommunications (OFTEL) changed the area codes in Inner and Outer London as well as Northern Ireland. It also meant that different codes were assigned to specific categories of numbers:

  • 00 — International codes
  • 01 — Existing area codes
  • 02 — New area codes and local numbers
  • 03 — New numbers for the future
  • 04 — New numbers for the future
  • 05 — New numbers for the future
  • 06 — New numbers for the future
  • 07 — Mobile phone, pager and personal numbers
  • 08 — Special rate numbers
  • 09 — Premium rate numbers

The 'Big Number Change' also increased the length of telephone numbers to 8 digits and changed the London prefix to '020'.

Telephone Numbering Plan

In 2003, OFTEL proposed the creation of the National Telephone Numbering Plan, which was designed to change the area names that British Telecom (BT) had once used. This numbering plan means that telephone numbers are assigned to subscriber stations.

As a result of this numbering plan, nearly every geographic phone number has ten digits after the trunk code '0'. Area codes range between two digits and five, with the three-digit area codes being the only ones to be assigned to the five main cities that were 'Directors' and also the areas Tyne and Wear, County Durham, and Northumberland.

Two-digit area codes always have eight subscriber numbers ad start with the prefix '02'. This is the newest phone number format and is assigned to Northern Ireland.

Our list of UK area codes allows you to search by a specific area code or by location.

Currently, phone companies operate using a telephone system called the Public Switched Telephone Network (PSTN), which is due to be phased out by 2025 as it is becoming too complicated and expensive to maintain. So, is the landline about to be defunct? No, it's just getting an upgrade.

What that means is you will still be able to use your landline with minimal disruptions, and the home phone numbers you've likely memorised will still be in use. The only real difference will be that the calls you make will use a broadband-based connection rather than the old copper network that landlines usually run on.

You will not need to do anything to instigate the switch to digital as telephone service providers will contact you to let you know how the change over will work and whether you need to upgrade your phone to work with the new system.