United Kingdom telephone numbers

Location of the United Kingdom (dark green)
Location
Country	United Kingdom
Continent	Europe
Access codes
Country calling	+44
International call prefix	00
Trunk prefix	0
Dial plan
Regulator	Ofcom
Type	Open
NSN length	10 mostly; 9 in some 01xxx areas, 9 in one 01xxxx area, 9 for all 0500 numbers, 9 for some 0800 numbers; 7 for two special 08xx numbers.
Typical format	NSN = 10: (01xxxx) xxxxx (01xxx) xxxxxx (01x1) xxx xxxx (011x) xxx xxxx (02x) xxxx xxxx 03xx xxx xxxx 055 xxxx xxxx 056 xxxx xxxx 070 xxxx xxxx 07624 xxxxxx 076 xxxx xxxx 07xxx xxxxxx 0800 xxx xxxx 08xx xxx xxxx 09xx xxx xxxx NSN = 9: (016977) xxxx (01xxx) xxxxx 0500 xxxxxx 0800 xxxxxx NSN = 7: 0800 1111 0845 46 4x Notes: 01 ranges can have NSN as 10 or 9. 0800 range can have NSN as 10, 9 or 7. 0845 range can have NSN as 10 or 7. 0500 range has NSN as 9 only.
List of United Kingdom codes

The UK telephone numbering plan, also known as the National Telephone Numbering Plan, is the system used for assigning telephone numbers in the United Kingdom and the Crown Dependencies. It is regulated by the UK government's Office of Communications (Ofcom), which holds responsibility for telecommunications.

Overview[link]

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^[1] 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 <area code> <local number> 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.

Format[link]

Geographic numbering[link]

• (01xxx) xxxxxx

This is the format used by most areas. It has a four-digit area code (after the initial zero) and a six digit subscriber number, and is known as 4+6 format. These area codes were changed by adding a "1" directly after the initial zero as a part of PhONEday in 1995. Just short of 581 areas use this format, and the area codes range from 01200 to 01998 (except those that match the pattern 1x1 after the initial zero). A small number of these areas also have a few subscriber numbers that have only five digits. That is, almost all (01xxx) area codes now have only six digit local numbers. e.g.

• (01xxx) xxxxx

This is used for forty smaller towns where some subscriber numbers within the area code have only five digits^[2] and is known as 4+5 format. The numbers therefore have only nine digits after the initial zero trunk code. These area codes were changed by adding a "1" directly after the initial zero as a part of PhONEday in 1995. These towns always have a mixture of six and five digit local numbers, each type allocated in specific DE blocks; e.g. in the 01647 area code numbers beginning 24xxx and 61xxx have five digits whereas all other DE blocks within that area code are allocated as six digit numbers. The number of places with five digit subscriber numbers and an 01xxx area code has declined rapidly in recent decades. There were 511 ranges allocated across 56 different area codes in January 1998. The Big Number Change removed many, especially in Northern Ireland, and by July 2005 there were only 329 ranges in 42 codes. By April 2010 this had reduced to 324 ranges in 40 codes, with the same number still in use in January 2012. e.g.

• (01x1) xxx xxxx

This is the geographical number format for the first round of five large cities moved to all figure dialling in the 1960s, and subsequently also used in the metropolitan county of Tyne and Wear, eastern County Durham and south-eastern Northumberland from the 1980s onwards. These six areas have a three-digit area code matching the pattern 1x1 (after the initial zero) and a seven digit subscriber number, and this is known as 3+7 format. These area codes were changed by adding a "1" directly after the initial zero as a part of PhONEday in 1995. The first three digits of the local number identifies a small area within the city.

• (011x) xxx xxxx

This is the geographical number format for the second round of large cities and towns moved to brand-new three-digit area codes. Five of these were moved in 1995 as a part of PhONEday. Reading followed a year later. At the time of the change, an extra digit was added to the subscriber number. These six areas have a three-digit area code matching the pattern 11x, with a seven-digit subscriber number, and this is known as 3+7 format. The first three digits of the local number identifies a small area within the town or city. Note that the former Reading area code had already been changed once, by adding a "1" directly after the initial zero as a part of PhONEday in 1995.

• (02x) xxxx xxxx

This is the newest geographical number format. It is used for the third tier of large cities and for Northern Ireland, and was formed as a part of the Big Number Change in 2000. The new area code is much shorter than the old one, and begins 02 unlike the previous 01 area codes. Numbers in these five areas are commonly misquoted, e.g. London as 0207 or Cardiff as 02920. The numbers consist of a two-digit area code matching the pattern 02x, and an eight-digit subscriber number, and this is known as 2+8 format.

The first four digits of the local number identifies a small area within the town or city. At the time of the change, the subscriber part of the number gained an extra digit in London, those in Northern Ireland gained two or three digits, and the subscriber part of the number in the other areas gained two digits. All of these areas were also subject to a previous code change, one that added a "1" directly after the initial zero, as a part of PhONEday in 1995. The short area code is also known as a wide area code.

• (01xxxx) xxxxx and (01xxxx) xxxx

This is the oldest geographical number format and is used for twelve smaller towns and villages where the subscriber number is either five or (in one area code) four digits long. These are known as 5+5 and 5+4 format. Note that therefore the STD code and the subscriber number does not always total ten digits after the initial zero trunk code. These area codes were changed by adding a "1" directly after the initial zero as a part of PhONEday in 1995. The number of places using these two formats has declined rapidly in recent decades and Brampton is the last place in the UK with four-digit local numbers.

The above twelve area codes and their six 'parent' area codes (01387, 01524, 01539, 01697, 01768 and 01946) are known as 'Mixed' areas due to multiple area codes sharing the same SABC digits.

National Dialling Only ranges[link]

These ranges have subscriber numbers beginning with the digits "0" or "1", e.g.:

Currently, these numbers are mostly used as the termination points for non-geographic numbers, and by some automated systems such as alarms. As such they are not usually meant to be directly dialled. These numbers have been problematic as some mobile phone operators in the UK do not allow access to these ranges^{[citation needed]}, and there may also be difficulty accessing these numbers from outside the UK. Regulator Ofcom proposes that in future these numbers be released for wider, general-purpose use in up to 70 area codes facing number shortage.^[5] In order to avoid confusion with codes beginning with these digits, the area code must always be dialled, even from within the same geographic exchange. Accordingly, if these numbers are eventually released for general use, Ofcom proposes completely removing the ability to dial locally without the area code in areas affected.

Mobile telephones and personal numbering[link]

• 07xxx xxxxxx—mobile phones, pagers, Personal Numbering and WiFi numbers.

Individual mobile phone companies are allocated different ranges within the 074xx, 075xx, 07624, 077xx, 078xx and 079xx area codes. Changes to mobile phone numbers in the Big Number Change were mostly straight replacements, such as Vodafone customers on the 0378 block became 07778.

Since the advent of Mobile number portability, mobile phone number prefixes can no longer be relied on to determine the current operator of a particular mobile phone – only the original operator.

Non-geographic numbering[link]

• 03xx xxx xxxx—"UK-wide" numbering.

On 27 July 2006, Ofcom announced that companies will soon be able to use an "03" non-geographic number, in place of other non-geographic numbers (such as 0870 or 0845 numbers). Callers would be charged at the same rate as if they were calling a geographic number (01 or 02).^[6] This means that customers who are benefiting from "free" minutes on mobile phones or landlines would also be able to call these numbers using their inclusive minutes.^[7] On 13 February 2007, Ofcom released more details on their plans for the 03 range and announced that allocations of 03 numbers to providers would begin in March 2007. Whilst 01, 02 and 07 numbers can receive text messages, currently the majority of cellular network providers do not support the sending of text messages to 03 numbers. Three different ranges of numbers were announced; those beginning 0300/0303 are reserved for qualifying public bodies and non-profit organisations, those beginning 0330/0333, which are available for allocation to anyone, and those beginning 034x/037x which will be used for migration from the 084x and 087x number ranges respectively. Ofcom itself began using 03 numbers on 13 November 2007 for public use.^[8]

• 05x xxxx xxxx—Reserved for corporate numbering.

Unlike 03 numbers there is no uniform pricing for 05 numbers; BT charge a number of different rates depending on the number dialled.^[9] Some are charged at geographic rate, others not, and unlike 03 numbers, other operators are not required to charge the same rates as BT for calling 05 numbers.

• 0500 xxxxxx—Freefone services allocated before 1999.

The 0500 range is used for some freephone services which were originally provided by Mercury Communications Ltd (now Cable & Wireless Worldwide). These numbers are different from the rest of the 05 range in that they are only 10 digits in length, e.g. 0500 2 88 2 91 (BBC Radio 2, 88 to 91 FM), as they were allocated before the 05 range was assigned to corporate numbering.

• 08xx xxx xxxx—Non-geographic fixed-rate, or special-rate services.

With the exception of 080x freephone numbers, these are charged above geographic rates, with the extra going to the terminating telco. This additional revenue may be shared with the subscriber, but is often used instead to subsidise additional network services, such as fax to email, virtual office applications, call queuing, voicemail and easy number redirection. There is widespread confusion about the cost of calling 084/087 numbers, with many major companies persisting in misdescribing them as "Local Rate", "Lo Call" or "National Rate". They often do not qualify for discounts and bundled minutes, and can be prohibitively expensive when called from mobiles and payphones. None of these services are exclusive to 08xx numbers, and could be provided on any number range. More affordable equivalent numbers can often be found via www.saynoto0870.com.

There are also several very short "special" numbers in these ranges, notably 0800 1111 for Childline and 0845 46 47 for NHS Direct.

• 09xx xxx xxxx—Premium Rate Content Services

Numbers in the 09xx range are charged at the highest rates of any calls within the United Kingdom, and are controlled by various regulations regarding their use. The regulator is PhonepayPlus, formerly known as ICSTIS. There are a large number of charge bands, some with high pence-per-minute rates, others with a high fixed-price for the entire call.

Crown dependencies[link]

• Guernsey, Alderney, Sark

• Jersey^[12]

• Isle of Man

On the Isle of Man, both fixed and mobile phone numbers can be dialled locally in the six-digit format..

Although calls from UK landlines to landlines in the islands are charged at the same rate as those to other UK landlines (i.e. they are not treated as international calls), calls may be excluded from calling plans offering unlimited UK fixed line calls, and some mobile operators may also charge more. Calls and SMS messages sent to island mobile phone numbers are not charged at the same rate as calls to UK mobile phone numbers.

Fictitious numbers[link]

Ofcom has also reserved certain number ranges for use in television dramas and films, so as to avoid the risk of people having their telephone numbers displayed, and receiving unwanted calls. This is similar to the use of fictitious telephone numbers in the United States and Canada with the digits 555.

In most of the large cities with three-digit area codes a range of numbers is reserved, usually all the numbers starting with the digits 496. For fictitious numbers in other areas the area code 01632 is reserved; this code is not in use, although 0632 was used for Newcastle upon Tyne until the late 1980s (63 = NE). There are also reserved ranges for fictitious mobile, freephone, and premium rate numbers.^[13][14]

The Post Office even produced dial centre labels for use in advertisements and film/TV with a mythical exchange called VINcent plus four digits. The numerical equivalent of VIN was 846 and all the caller got was the speaking clock (i.e. 846 is also numerical equivalent of TIM) in the big city "Director" areas.^{[citation needed]}

At around the same time as the other Big Number Change changes, Ofcom revised their recommendations to update the prefixes, add additional areas, and increase the size of the allocation from 10 to 1000 numbers per block. Those changes are listed in the Big Number Change article.

In Coronation Street, the fictional Manchester suburb of Weatherfield uses the unallocated range (0161) 715 xxxx.^[15]

Special service numbers[link]

Short codes beginning with 1 are reserved for telecom service providers' own functionality; some of the most well-known are codes for use with Caller Display:

The UK has two free emergency numbers—the traditional 999, which is still widely used, and the EU standard 112, which can be used in all member states of the European Union. Both 999 and 112 are used to contact all emergency services: Police, Fire Service, Ambulance Service, Mountain Rescue, Coastguard and Cave Rescue.

Both numbers can be called from mobile phones with the keylock on, or without entering the PIN where that would otherwise be required. Although some mobile phones allow emergency calls to be attempted without a SIM card, at present the UK networks reject such calls. Since November 2009, an emergency call can be made through any UK mobile network as long as there is a SIM for *any* valid UK network in the handset. More information about the 112 emergency number can be found at the 112 : The European emergency number web site.

The chargeable number 101 was introduced for non-urgent crime and community safety calls on a trial basis in 2006. In Wales, the scheme has been taken forward by all four police forces, who adopted the number for non-emergency calls on a permanent basis in early 2009. In England the scheme was on trial until 2012, when it was adopted nationwide and the cost to call changed from 10p per call to 15p per call.

The operator is obtained via 100, while directory enquiries, formerly 192, is now provided in the 118xxx range, e.g. 118 212, 118 800, 118 500, 118 118, by different companies. International Operator assistance is reached through "155".

From early 2010, the pan-European 116 number range comes into use for social helplines. The first three numbers likely to be issued are for Missing People who will use 116 000 for a missing children helpline, the NSPCC ChildLine on 116 111, and Samaritans who will use 116 123 for an emotional support helpline.

Fixed line telephone subscribers for BT,^[16]Virgin Media^[17] and TalkTalk have the opportunity to use an automated messaging service which takes messages when the called number is either engaged ("busy") or not answered within a given time. This can be accessed by calling 1571.

Since the mid 1990s speaking clock services have been available throughout Britain using the number 123. Before this, exchanges in "Director" areas (Birmingham, Edinburgh, Glasgow, Liverpool, London and Manchester) dialled 846 (TIM) (later changing to 123) and main exchanges in "Non-Director" areas originally used "952", later changing to "80" with the introduction of STD and eventually to "8081" as other recorded services were introduced on 80X1 codes. Some mobile operators allocate other services to 123—such as customer services or voicemail etc.

Two telephone helplines within the regular code space have only eight digits, namely 0800 1111 for ChildLine and 0845 4647 for NHS Direct in England and Wales.

History[link]

The telephone service in the United Kingdom was originally provided by private companies and local councils. But by 1912–13^[18] all except the telephone service of Kingston upon Hull and Guernsey had been bought out by the Post Office. The Post Office also operated telephone services in Jersey until 1923 and the Isle of Man until 1969 when the islands took over responsibility for their own postal and telephone services – although the Isle of Man system remained part of British Telecom until 1987.

Post Office Telecommunications was reorganised in 1980–81^[19] as British Telecommunications (British Telecom, or BT), and was the first major nationalised industry to be privatised by the Conservative government. The Hull Telephone Department was itself reconstituted as Kingston Communications, in 1987; it was sold by Hull City Council in the late 1990s and celebrated its centenary in 2004.

Director system[link]

In November 1922 the General Post Office decided to adopt the Strowger system from the various systems it had tried and it was to include "Directors" in the exchanges in London. Demonstration models of the "Director" exchange were shown by manufacturer ATM of Liverpool as part of the Post Office exhibits at the British Empire Exhibition at Wembley in 1924 and 1925. However, it was not until 1927 that the first "Director" telephone exchange was brought into service in Holborn, London and rolled out progressively across Greater London. A 3 digit code, represented by letters, identified the local exchange. Director schemes were gradually introduced in the other major cities of the UK — Birmingham, Edinburgh (although a relatively small city, it obtained seven-figure dialling for political reasons), Glasgow, Liverpool and Manchester.

Introduction of area codes[link]

Subscriber Trunk Dialling (STD) was introduced in 1958^[20] to allow a caller to call another telephone directly instead of via a manual telephone exchange operator. Uniform exchange codes, usually called STD codes, were allocated for every exchange in the country, progressively as STD was rolled out. This process was not completed until 1979.^[21]

The original concept was for STD to be a nationwide Director system, and in common with the Director system, the exchange codes were originally assigned based on two letters of the respective place's name and the corresponding numbers on a telephone dial. For example Aylesbury was given the STD code 0AY6, where the letter A can be found on the number 2 and the letter Y on the number 9. The letter O became a zero, such as for Bournemouth: 0BO2 where BO = 20. Originally, where a place's name began with the letter "O" the code would begin with two zeros, such as Oxford: 0OX2 where OX = 09. These codes starting with "00" were later reallocated, freeing the prefix 00 for use by calls to the Republic of Ireland, to radiophones and to premium rate numbers.

Within a single code group area there would usually be multiple exchange buildings in various locations. The smaller exchanges might have only a few hundred lines with three-digit subscriber numbers, e.g. 200–499. Larger exchanges might have a few thousand lines with four-digit subscriber numbers, e.g. 2000–5999. The main exchange in the group would usually have five-digit subscriber numbers e.g. 20000–49999.

Population growth over the next few decades meant there was a need for more lines. This would see an exchange with existing three-digit numbers open one or more new ranges with four-digit local numbers (e.g. 5000-6999), and exchanges with existing four-digit numbers open one or more new ranges with five-digit local numbers (e.g. 60000–69999).

Since number ranges were being reused in each local exchange within a group, a series of short codes was devised to allow dialling from one local exchange to another without the need to dial the full STD code. These short codes usually began with a 7, 8 or 9. The code was often only two or three digits, but might be up to five digits long.^[22]

The last digit of this short code would usually also feature as extra digits on the end of the main STD code in order to differentiate each satellite exchange within a group when dialling from another STD code area. In written form these area codes were split after the third digit to highlight this satellite exchange numbering.^[23]

e.g. for 0799, Saffron Walden (SW)

As time wore on and number shortages became more acute, local numbers were gradually converted to five-figure or six-figure numbers, and the STD code changed to the (0xxx) format. In many cases the initial digits of the new local number would be formed from digits previously at the end of the old STD code. The local number would be padded with extra fixed digits (if needed) to make up the new total length. In some cases the initial digits were changed e.g. Radwinter (079 987) 456 became Saffron Walden (0799) 500456, nowadays (01799) 500456.

Post 2000, only a dozen places have long STD codes with five-digit local numbers. One area with a long STD code retains four-digit local numbering. Long STD codes are rare. Many people are not familiar with the (0xx xx), nowadays (01xx xx) format; or the now discontinued (0xx xxx) format, and often omit the space in written form.

For the Director areas a 2 or 3 digit code was used for the city. These were:

The codes 071, 081, and 091 were reserved for later expansion, with the former two eventually being temporarily allocated to London (see below).

All figure dialling[link]

The use of names was intended to provide a mnemonic for the exchange in the same way as for the Director system, but as more and more places were given STD codes the mnemonic link became more and more obscure, and this system became unworkable. Also, international direct dialling was being introduced and as other countries (such as the USA) had different assignments of letters to digits the opportunity for confusion existed.

An earlier modification to get round this problem for European dialling was the addition of the letter Q to the digit 0, which previously represented only the letter O. This was because some French exchanges had alphabetic codes including Q, but in the event France moved to all-digit codes before direct dialling from the UK was introduced.

The use of alphabetic exchange (area) codes was abandoned in the UK in 1966 in favour of all figure numbering. As such about 60% of current area codes are still based on the original alphabetic STD.

Around 1982, the 091 code was also brought into use:

ELNS areas[link]

In certain areas of the country, it was sometimes decided that one area code would cover multiple charge groups. These are the so-called ELNS areas (Extended Linked Numbering Scheme) where the leading digit of the local number indicates which charge group the number belongs to. A diagram showing the principle is shown on page 9 of Oftel's telephone numbering guide^[24] and these areas are shown in the table below.^[25]

Calls to the Republic of Ireland[link]

Until the late 1980s, calls to major towns and cities in the Republic of Ireland could also be made using short codes starting with 000:

0001—Dublin 01 area

0002—Cork 021 area

0004—Dundalk 042 area

0005—Waterford 051 area

0006—Limerick 061 area

0007—Letterkenny 074 area

0009—Galway 091 area

This was discontinued in the late 1980s, so that all calls to the Republic of Ireland from the UK had to be dialled in the normal international format using the international access code (initially 010 until 1995, and then 00) and country code (353).

Calls could also be made using the full international dialling code since the introduction of International Direct Dialling.

While most of the Republic of Ireland could be direct dialled, a small number of rural areas did not have an automated telephone service until the 1980s. As a result, calls from the UK to these areas had to be made through the BT operator who connected the calls to their Irish counterpart for completion. Unlike other international calls, these were handled by the BT national operator, in the same way as UK operator calls. This service was withdrawn at noon on 28 May 1987 when the last manual exchange in Ireland, at Mountshannon, County Clare, was switched over to an Alcatel E10 digital exchange. This completed Telecom Eireann's rural digitalisation project.

Although full international dialling is now used, calls from Northern Ireland landlines to landlines in the Republic are charged at UK national or local rates, and calls from Great Britain to the Republic are charged at a special "Republic of Ireland" rate, higher than inland rates, but lower than those for elsewhere in Western Europe. Additionally, calls to Northern Ireland from the Republic of Ireland can be made without an international access code, but instead replacing the British 028 prefix not with the conventional international prefix 00 44 28 but with a shorter Irish 048 area code which specifically covers Northern Ireland. For example, calling Belfast from London would be 028 9xxx xxxx while calling Belfast from Dublin would be 048 9xxx xxxx.

Number shortage[link]

With growth in second phone lines, direct dial-in (DDI) lines, fax machines and multiple telecoms operators during the 1980s the demand for telephone numbers exceeded the available number ranges. A number of changes were to be made to the UK numbering plan. All these stages were planned out in one exercise in the early 1980s, though the exact dates for each stage was decided later.

Splitting 01 for London into 071 and 081[link]

The first major change was in May 1990, when the London 01 area code was replaced with 071 and 081. Local numbers remained seven digits long. Exchanges in central London used the 071 code. The remaining exchanges now used the 081 code and formed a ring around the 071 area.^[26] Although this effectively doubled the available numbers from eight to sixteen million, it was not to be the last change for the capital.

This change freed up the entire 01 code range for the next step of the plan: converting all geographic area codes to 01. That operation would then free up the whole of the 02 to 09 range for a future re-organisation of some geographic and all mobile and non-geographic numbers. Most areas would see two code changes over the next decade, whilst London would have a total of three. It would be a decade before this inner/outer London split was eventually nullified.

Consumers were already becoming confused as to what they would be charged for any particular call, with for example (0404) xxxxx being a call to Honiton in Devon and (0403) xxxxxx being a much more expensive call to a mobile phone. The situation in the early 1990s was as follows:

The next few changes would fix these problems.

PhONEday[link]

Geographic numbers[link]

On "PhONEday", 16 April 1995, the digit "1" was inserted into all UK geographic area codes. Promotion of this day included special Easter eggs. Under the new changes, for example, Inner London's 071 became 0171; Outer London's 081 became 0181. A small selection of the codes that changed are shown in the table below:

This was done with a view to reorganising the numbering plan at a later date, so that the first two digits would indicate the type of service called:

The international access code also changed on "PhONEday", from 010 to 00 thus meeting the international call prefix standard set by the International Telecommunications Union (ITU).

Five new area codes were introduced for cities that were running low on phone numbers—and a digit was prepended to each existing local number.

Most of the initial local number ranges created by PhONEday were exhausted within just a few years. New local numbers then began to be allocated with a different initial digit. For example, in Sheffield (0114) when the 2xx xxxx numbers were exhausted, new numbers (other than old recycled ones) then began to be issued from the 3xx xxxx range. Similarly, newly allocated numbers in Leeds (0113), Leicester (0116) and Bristol (0117) also came from the 3xx xxxx range, but in Nottingham (0115), the new numbers instead came from the 8xx xxxx range.

Less than a decade later, further new ranges were opened in most of these areas, but this time new Reading and Leicester numbers are in the 4xx xxxx range, new Bristol numbers are in the 2xx xxxx range, new Nottingham numbers are in the 7xx xxxx range and new Leeds numbers are in the 4xx xxxx and 8xx xxxx ranges.^[28]

National dialling only numbers[link]

Changes between PhONEday and the Big Number Change[link]

Geographic numbers[link]

Reading numbers endured two changes in a very short time. PhONEday, on 16 April 1995, changed the area code from 0734 to 01734, and then almost a year later, on 8 April 1996, it changed again to (0118). At that time, local numbers were changed from six to seven digits by inserting a 9 in front of the old local number. Parallel running of the old numbering was withdrawn on 9 January 1998.

Around this time, some new number ranges were already being allocated and used for mobile phone numbers. These new ranges already fitted into the new numbering scheme of 07xxx xxxxxx. The rest of the older mobile phone numbers, those already in use for many years (and at that time, both one-digit shorter, and having codes scattered throughout the 03 to 09 range) would be brought into this 07x numbering scheme a few years later, both by changing the code to the 07x range, and by adding an additional digit.

National dialling only numbers[link]

Big Number Change[link]

Geographic numbers[link]

On 22 April 2000 the second phase of the plan came into operation, dubbed the "Big Number Change". With 02x area codes freed up by the previous reorganisation, they could be re-used. These areas had already had a code change (to insert a "1") five years earlier as a part of PhONEday. The Big Number Change altered the area codes again, as well as making the local number two digits longer (London: one digit longer).

Note that although Southampton and Portsmouth are one code from a code structure and local dialling point of view, as of January 2006 calls between them are not local calls and the "codes" (023) 8xxx and (023) 9xxx are treated as separate by the BT site for determining local call area.

It is planned that the new codes will eventually cover a larger area than at present. For example, although (029) currently covers just the Cardiff area, it may in the future cover all of Wales.^[31]

The code for Northern Ireland is (028). The transition codes for Northern Ireland are shown below. These can be accessed from the Republic of Ireland using either the domestic code 048, or the international prefix 00 44 28.

The prefixes for existing numbers in Northern Ireland are split up into seven groups, roughly based upon the county in which the main exchange is based. The initial digit of each phone number is based on the designated county—for example, the first county alphabetically is County Antrim so numbers in this county start with 2. The next county is County Armagh so numbers here start with 3. One exception to this is the Greater Belfast area, initial digit 9, which is extended to include each adjacent former STD code area, including the towns of Bangor, (County Down) (91), Lisburn (92), Carrickfergus (93), Antrim (94) and Saintfield (97). The encompassed former STD codes at some points extend to over 20 miles from Belfast itself. There is a much more complete list in the Big Number Change article.

National dialling only numbers[link]

Non-geographic, and mobile and pager numbers[link]

In addition, mobile and pager numbers were all moved into the 07xxx range. Pagers moved into 076xx, while personal numbers moved to 070. Mobile phone numbers moved into the 077xx, 078xx and 079xx ranges (and more recently, 075xx and 074xx have also been brought into use).

The exception to this was Manx Telecom mobile phone numbers, where the code became 07624 in order to match the 01624 used for landlines.

In addition, lower and higher rate non-geographic numbers (previously called lo-call or local-rate and national-rate numbers, though these terms are no longer recommended to be used as they can be misleading [1] [2]) migrated to 08xx and premium rate numbers migrated to 09xx.

A summary of the migration path for the existing mobile and pager codes, as they were at the time, is shown below:

020 for London[link]

The number change meant that London returned to a single area code again (as in the old 01 days), with no "inner/outer" split. Existing London numbers acquired the prefixes 7 or 8, but from that point on (020) 7xxx xxxx and (020) 8xxx xxxx numbers were assigned or reused anywhere in the London area covered by the single (city-wide) 020 code.

From June 2005 the regulator, Ofcom, ceased to allocate new number blocks to suppliers in the 7xxx xxxx and 8xxx xxxx ranges. From this date onwards all number allocations were in the 3xxx xxxx range and can be used anywhere in the London 020 area. Although new blocks of 7xxx xxxx and 8xxx xxxx range numbers are no longer being allocated to suppliers, those that have not yet exhausted their existing blocks are able to continue to issue and re-issue them to their customers.

Numbers in the 020 0xxx xxxx and 020 1xxx xxxx number ranges have also been made available. However, these numbers cannot be dialled without the 020 code and are called "national dialling only" numbers. A small number of these blocks are used by numbers migrated from old 0171-0xx xxxx, 0171-1xx xxxx, 0181-0xx xxxx, and 0181-1xx xxxx "national dialling only" numbers. They are mainly used as termination points for non-geographic numbers, and for various alarm and other automated systems where the actual telephone number itself is never called.

It is a common misconception that London still has more than one area code (i.e. "0207" and "0208").^[33] This is incorrect in the sense that omitting the "0207" or "0208" (area) code will give a local number that cannot be connected as it is missing the first digit. Therefore, writing a London number as 020x xxx xxxx is incorrect and can lead to confusion when attempting to dial it.^[34]

Misconceptions[link]

The misconception of area code and number separation is also seen in other areas of the country where the area code length was reduced in the Big Number Change such as Coventry being written as 02476 xxxxxx, whereas the correct number sequence is (024) 76xx xxxx (Coventry now has some (024) 77xx xxxx numbers) and Cardiff being written as 02920 xxxxxx whereas the correct number sequence is (029) 20xx xxxx (Cardiff now has some (029) 21xx xxxx numbers).

Likewise in Portsmouth, numbers are being incorrectly written as 02392 xxxxxx, whereas the correct number sequence is (023) 92xx xxxx (Portsmouth now has some (023) 93xx xxxx numbers).^[35]

This also occurs in some areas of Northern Ireland, that previously had 5-digit and 6-digit local numbers like in Banbridge (previously (018206) xxxxx), where numbers are still erroneously written as 028406 xxxxx instead of (028) 406x xxxx. Locals still misquote the area code as 028406, seven years after the change. The same occurs in formerly six-digit code areas, such as Lisburn (previous (01846) xxxxxx) continues to frequently appear as 02892 xxxxxx instead of the correct form (028) 92xx xxxx.

This is also seen in the earlier PhONEday areas, such as in Sheffield, for (0114) 2xx xxxx numbers, where these are often seen written as 01142 xxxxxx or are missing the leading digit 2 when abbreviated (751234 instead of 275 1234 for example).^[36] This is a particular problem now that (0114) 3xx xxxx local numbers are being issued.^[37]

It also affects Reading numbers where these are still being written as 01189 xxxxxx, whereas the correct number sequence is (0118) 9xx xxxx. Now that Reading has some (0118) 3xx xxxx and (0118) 4xx xxxx numbers mis-dialling also occurs when people prefix 3xx xxxx and 4xx xxxx numbers with 01189 instead of just 0118.^[38]

In all of these areas, the result of the confusion is that callers are adding an incorrect area code to numbers allocated within the new local number ranges, and that then results in a mis-dialled call.

Recent changes[link]

2003 area name changes[link]

In 2003, Oftel published a proposal^[39] to create a National Telephone Numbering Plan. This draft plan proposed changing the names of many areas from whatever name BT had previously used. Following responses from BT,^[40] C&W^[41] and others, the final plan was published with a number of amendments incorporated,^[42] followed by a minor revision a few weeks later.^[43] A few months later, the data and the responsibility for maintaining it was passed to Ofcom.

Ofcom's data is contained in two files: the NTNP PDF file^[44] (updated several times per year) and the SABC CSV file^[45] for electronic download (published weekly). Although the data in these files should be identical, there have been and still are very many differences between them.

In one background document^[46] from 2004, Ofcom states that In order to conform to the National Telephone Numbering Plan (NTNP), the names of the following Geographic Area Codes have changed - 1248, 1268, 1275, 1276, 1291, 1293, 1306, 1322, 1327, 1334, 1344, 1354, 1356, 1375, 1384, 1394, 1425, 1438, 1442, 1451, 1454, 1461, 1470, 1471, 1477, 1478, 1485, 1488, 1489, 1491, 1543, 1561, 1562, 1582, 1588, 1598, 1661, 1668, 1675, 1680, 1681, 1684, 1688, 1689, 1695, 1707, 1720, 1727, 1737, 1744, 1753, 1770, 1784, 1806, 1821, 1856, 1870, 1877, 1883, 1885, 1889, 1895, 1908, 1920, 1922, 1926, 1928, 1932, 1952, 1953, 1963, 1980, 1983, 1984, 1992.

However, several of the above area codes did not see any name change. It had been proposed to change some names but in the end either the original BT name continued to be used or a completely new name suggested by either BT or C&W, or by both, was adopted. The Ofcom proposal^[39] also contained a large number of spelling mistakes in the proposed area code names. Some of those errors were rectified within weeks or months, while others have still not been fixed eight years later. Additionally, several other areas changed their name after suggestions by BT and/or C&W, although Ofcom originally had no plans to change them. There are also several areas which changed name but are not listed above. Additionally some names were changed in one Ofcom document but were not updated in the other Ofcom document until several years later. Some have still not been updated or corrected.

Nine more place names were fixed in a reissued NTNP PDF document in mid-December 2011.^[47]

The proposed and actual changes, along with the list of implementation errors, are detailed below.