History of telephone numbers in the United Kingdom

Director system

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

Subscriber Trunk Dialling (STD) was introduced in 1958 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.

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, or 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.

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.

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 e.g. Newport (079 982) 5678 became Saffron Walden (0799) 825678, nowadays (01799) 825678. The local number would be padded with extra fixed digits (if needed) to make up the new total length e.g. Clavering (079 985) 345 became Saffron Walden (0799) 850345, nowadays (01799) 850345. 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.

Director areas

The director areas used a shorter area code, usually in the form 0x1 (01 for London) with a 7-digit local subscriber number. 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).

Within the director areas, the first three digits of the seven digit subscriber number would relate to the local telephone exchange on which the number could be found. These were usually three-digit letter codes, based on the first three letters of the exchange name e.g. within the Liverpool director area, a number on the Anfield telephone exchange would be dialled as ANField xxxx. Within the London director area, a number on the Frobisher telephone exchange would be dialled as FRObisher xxxx.

After the introduction of STD, but before the advent of all-figure dialling, to call a number on an exchange in a director area, the number would be dialled as follows, for example, OL1 ANF 1234. After the advent of all-figure dialling the number would be 051 263 1234.

1968 area code changes

In 1968, area codes beginning 00 were changed.

Codes beginning 00 were also used for premium rate numbers or as a short code for dialling calls to various places in the Republic of Ireland over the next few decades.

All figure dialling

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:

Special services

Until the mid-1980s freephone numbers could be accessed only by ringing the operator on 100 and asking to be connected, e.g. Freephone 8963 for BT customer service. Later on, the 0800 code came into use for freephone services. These numbers often had only 8 digits, e.g. 0800 1111 for ChildLine.

From around 1980, calls to Radiophones could also be direct dialled.

0034—Area 1 (Greater London) 0036—Area 2 (Severn and Midlands) 0037—Area 3 (Liverpool and the North-East) 0033—Area 4 (Southern and Eastern Scotland) 0039—Area 5 (Southern England)

These covered only a small part of the country. The 0035 and 0038 codes were added later.

In the 1980s, these other allocations were also in use:

0055—"Talkabout" 0066—"Super Call" 0072—Radio Paging 0073—Radio Paging 0077—"Super Call"

Calls to the Republic of Ireland

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

and

0015—Sligo

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 Éireann's (now called eircom) 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. However, it is also possible to make calls using the normal international 00 44 28 xxxx xxxx format. In both cases, calls are charged at a much lower rate than calls to Britain. In recent years, these arrangements are becoming less relevant as customers in both countries have access to a wide range of telephone service providers, cable telephony services, mobile operators and alternative services based on VoIP. Some providers include unlimited calls to the UK or Republic of Ireland (and many other countries) in various bundled packages.

Mixed areas in Northern Ireland

In Northern Ireland, many of the area codes were created as "mixed" areas. There were a number of code changes within Northern Ireland over the years with some exchanges swapping to different area codes.

In 1993, further changes were made throughout Northern Ireland in preparation for PhONEday in 1995. Many of the changes were eliminating 3-digit and 4-digit subscriber numbers in rural exchanges by adding extra digits; the table below shows the end result. The system of "mixed" areas remained in place.

Additional codes for mobile, freephone, non-geographic, premium rate and pagers

The prefixes listed in the table below were introduced at various times from the early 1980s to the mid-1990s. The details and timeline of these allocations is complex.

0459, 0802, 0831, 0839, 0860, 0881, 0891, 0893, 0897, 0898, 0921, 0941, 0961, 0979, 0987, 0998 and 0999 had never been used for geographic area codes, so could be used for non-geographic and mobile services as soon as the need arose. Those codes, if used, have since migrated to various 07, 08 and 09 ranges in the Big Number Change.

Other codes had multiple uses over the years. Edinburgh stopped using 0500 and moved to 031 (0131 after PhONEday). Some years later, 0500 was used for Mercury Freephone services.

Langholm was moved from 0541 to the new 038 73 "mixed" area (0138 73 after PhONEday). 0541 5 was then re-allocated as the National Rate non-geographic code for C&WC AreaCall which then became 0870 15 in the Big Number Change.

Hornsea was moved from 0401 to join with the existing Patrington allocation at 0964 (01964 after PhONEday). This created the 0964 Hornsea and Patrington ELNS area. 0401 later went on to be used for Cellnet mobile until moving to 07701 in the Big Number Change.

Some prefixes had dual usage when no longer used for geographic area codes. In the former Basildon 0374 area code, the 0374 5 number block was used for National Rate calls while the rest of the 0374 range was used for Vodafone mobile phones. Likewise, in the former Weardale 0956 area code the 0956 7 block was used for personal numbering and the rest of 0956 was used for One-to-One mobile telephones.

The area codes 0921, 0987, 0998 and 0999 were never used., the last of which due to possible confusion with the 999 emergency number.

Rapid expansion of mobile and premium rate services quickly depleted the number of available area codes. By the early 1990s it was also becoming more difficult to remember the various codes that might cost a lot more to call than a local or national call, and many consumers were caught out with larger than expected bills. A more long-term solution would need to be found as it was clear that mobile usage in particular was going to push demand for new codes even further in the coming years.

Number shortage

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

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. 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.

Initial allocations with 10 digits: freephone 0800 numbers

The longest telephone numbers in use until now had been 9 digits long (not including the 0 trunk code), e.g. 051 234 5678, 0303 456789, 03873 56789, 0800 445566. The long term plan is for migration to 10 digit numbering in the UK and in 1991 this started with new 0800 numbers being allocated with 10 digits.

Oftel administers number allocation from 1994

With multiple operators joining the market, administration was passed to an independent regulator. Oftel took over administration of the UK’s telephone numbers from BT in 1994.

Geographic numbers

On "PhONEday", 16 April 1995, the digit "1" was inserted into all UK geographic area codes, including those in the director, all-figure dialling, ELNS and mixed areas. 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 and second digits would indicate the type of service called:

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. Since then, other ranges have been opened in these areas. See table above for further details.

International calls from the UK

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).

112 emergency number in addition to 999

In 1995, the United Kingdom adopted the pan-European 112 emergency services number. This new number runs alongside the existing 999 number, first introduced in 1937.

Geographic numbers

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.

National dialling only numbers

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 another digit.

New personal numbers with revenue-share start using 070

In 1995, the 070 prefix began to be allocated for personal numbers (PNS). These new numbers had 10 digits.

New numbers at 070 107x xxxx were held aside in order for FleXtel personal numbers at 0956 7xxxxx to migrate in the forthcoming Big Number Change in 2000.

The geographic area codes 0700 to 0709 had only recently been moved to 01700 to 01709 on PhONEday. New 070 personal number allocations had to be chosen carefully such that mis-dialled calls for old pre-PhONEday geographic numbers would fail to connect rather than connect the caller to a user of a new personal number. Oftel identified old (070x) xx geographic number ranges that had not been used before and re-allocated those first.

For example, The Welwyn Garden City (0707) 4x range (now 01707 4x) had never been used, so 070 74xx quickly came into use for personal numbering in 1996. However, the (0707) 3x range (now 01707 3x) had been in use within Welwyn Garden City, and these numbers remained protected by Oftel for a number of years. The 070 73xx range of numbers finally came into use for personal numbering in 2007.

070 numbers initially allowed revenue share. These numbers are easy to mistake for mobile phone numbers and many scams developed. Oftel consulted on various proposals. Eventually revenue share was banned on these lines and they also fell under the jurisdiction of ICSTIS (nowadays PhonepayPlus), the premium rate services regulator.

New mobile numbers start using 077xx, 078xx, 079xx

Geographic numbers had been moved to begin 01 in the PhONEday changes in 1995. Pre-existing mobile phone, non-geographic, premium rate and pager services continued to use the same 9-digit 02xx xxxxxx to 09xx xxxxxx numbers as before. It would be several more years before these would add a digit to become 10-digit numbers and move to the 07, 08 and 09 ranges in the Big Number Change in 2000-2001.

From May 1997, new mobile phone services started using numbers beginning 077, 078 or 079 re-using area codes recently vacated by 9-digit geographic numbers. These new mobile numbers have 10 digits.

BT Cellnet started with 07801 xxxxxx, 07803 xxxxxx, 07808 xxxxxx and 07809 xxxxxx. Vodafone started with 07771 xxxxxx and 07775 xxxxxx in May 1997. One2One started using 07804 xxxxxx and 07806 xxxxxx numbers in May 1995. 07xxx codes for new allocations by operators have been issued by Oftel since May 1997. It would be another few years before older BT Cellnet 0802 xxxxxx numbers were converted to 07802 xxxxxx, Vodafone 0370 xxxxxx numbers were converted to 07770 xxxxxx and One2One 0961 xxxxxx numbers were converted to 07961 xxxxxx in the Big Number Change.

New pager numbers start using 076

Pre-existing pager numbers were already scattered under various codes in the 02xx to 09xx range and had 9 digits. Several services used non-standard 01 numbers. These would all eventually be moved to 076 codes and to 10 digits in the Big Number Change in 2000.

From 1998 onwards, new pager numbers began to be issued in parts of the 076 range. These new numbers had 10 digits.

Various parts of the 076 range were set aside for pager number migration in the forthcoming Big Number Change in 2000.

The number range 07624 xxxxxx was set aside for mobile telephones in the Isle of Man. This would also come into use as a part of the Big Number Change.

"08" consumer protection

The initial plan for the new "08" number range was such that rates charged to people calling an 08 telephone number would be made more clear by linking the cost of the call to the second digit of the National Significant Number. Numbers starting 080 would be free (except from mobile phones), while 082 would be cheaper than 089.

New freephone numbers start using 0808

In 1997, Oftel released 10-digit numbers beginning 0808 designated as freephone services. These calls are free only from a landline or public payphone.

Both BT and Mercury issued only 10-digit freephone numbers to users after 1997. With the market opened up to competition, many other companies also allocated these numbers to users.

Usage of pre-existing 10- and 9-digit 0800 numbers and pre-existing 9-digit 0500 numbers continued as before.

Additionally, numbers in the range 0808 80x xxxx are reserved for not-for-profit helplines and as such are usually free to call from most mobile telephones. A number of other numbers can also called for free from mobiles, but this varies by network.

New non-geographic revenue-share numbers start using 0845 and 0870

From 1996 onwards, Oftel brought various new 10-digit non-geographic 0845 and 0870 numbers into use.

Only certain sub-parts of each code were made available for immediate use. Numbers at 0845 7, 0845 9, 0870 1, 0870 4, 0870 5 and other ranges were set aside for numbers such as 0345, 0374, 0541, 0645 and 0990 that would be migrating from 9-digits to 10-digits and to these two 08xx codes in the forthcoming Big Number Change in 2000.

In these early days, the price for calling 0845 numbers from landlines was tied to BT's price for calls to local geographic numbers. Similarly, the price for calling 0870 numbers from landlines was tied to BT's price for national calls to geographic numbers.

1997 to present day: new allocations within existing 011x areas

These are detailed as extra entries within the PhONEday section above.

2000 introduction of 055 corporate numbers

In 2000, Oftel started allocating 055 numbers for corporate numbering. These numbers have 10 digits. Uptake of these numbers has been low.

055 114x xxxx numbers have been used for the BT Broadband Voice service since December 2003, one of their bigger customers being Abbey (now Santander) bank.

2000 introduction of 0844 and 0871 non-geographic revenue-share numbers

In 2000, Oftel started allocating non-geographic 0844 and 0871 revenue-share numbers. These numbers have 10 digits. Initially, uptake of these numbers was low, but increased dramatically from 2005 onwards.

These numbers look similar to 0845 and 0870 numbers but are often charged at a different rate. From their inception until around 2005, call costs from landlines looked like this:

080x—No charge to caller 0844—Up to 5p/min from BT landlines, set by terminating operator 0845—Originating landline operator's "Local Rate" 0870—Originating landline operator's "National Rate" 0871—Up to 10p/min from BT landlines, set by terminating operator

The call price for 0844 and 0871 numbers from a BT landline is the revenue-share premium and no additional markup, by regulation. From landlines other than BT, the call price for 0844 and 0871 numbers is usually higher than from BT landlines as those other operators add their own unregulated markup on top of the revenue share.

From mobiles, 080 numbers cost from 10 to 30 pence per minute and calls to 084 and 087 numbers cost up to 50 pence per minute at that time. The revenue share is only a small proportion of the cost billed to callers when using a mobile.

After 2005, most landline providers no longer differentiated between local and national calls, charging a single geographic rate for calling 01 and 02 numbers nationwide. Many landline providers also started offering inclusive call bundles for 01 and 02 numbers and by 2011 the vast majority of landline phone users were on this type of deal. Bundled minutes from mobiles include 01, 02 and 07 numbers. Bundles effectively make all calls to 01 and 02 numbers "free" for very many people. Since 2005, it has been illegal to describe 084 numbers as "local rate" or "lo-call" or 087 numbers as "national rate".

A small number of landline providers and a smaller number of mobile providers have allowed 0870 (and a few landline providers have also allowed 0845) numbers to be used in inclusive minutes bundles. However, 0844 and 0871 numbers are never inclusive. From landlines, 084 and 087 numbers cost anything up to 20 pence per minute. From mobile phones, 084 and 087 numbers cost anything up to 45 pence per minute. The price includes a revenue-share "premium" or "service charge" of up to 5 pence per minute for 0844 numbers and up to 10 pence per minute for 0871 numbers. The premium is passed on to the terminating telecoms company.

Due to persistent abuse of 0871 numbers these have been under the remit of PhonepayPlus (previously known as ICSTIS) since 2009.

In 2013/2014, the Consumer Rights Directive will make 084, 087 and other numbers charged at above geographic rate, illegal to use for customer service and complaints lines.

2001 introduction of 091x premium rate numbers

In 2001, additional premium rate numbers in the 091x range started to be allocated. Initially just 0911, but latterly also 0912 and 0913.

09 numbers were regulated first by ICSTIS and then after 2007 by PhonepayPlus.

2002 introduction of 118 xxx numbers to replace 192 directory enquiries

Until 2002, the domestic directory enquiries service within the UK had been reached by dialling 192 from a landline. The service had been run solely by BT. In December 2002, the market was opened up by Oftel for new providers to run additional directory enquiries services in competition. BT's 192 service moved to 118 500, and dialling 192 ceased working in August 2003. New providers used 118 118, 118 247, 118 855 and many others. Nowadays there are more than a hundred such providers and more than 130 different tariffs.

As with 09xx premium rate numbers, the usage of 118 xxx directory enquiry numbers was regulated by ICSTIS (later PhonepayPlus).

2003 new 0908 numbers for adult services

In 2003, the 0908 number range came into use, as 0909 was now almost fully allocated.

2003 area name changes

In 2003, Oftel published a proposal 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, C&W and others, the final plan was published with a number of amendments incorporated, followed by a minor revision a few weeks later. 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 (updated several times per year) and the SABC CSV file 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 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 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.

2003 responsibility for UK telecommunications passed from Oftel to Ofcom

In 2003, the Office of Telecommunications (Oftel) was disbanded and replaced with the Office of Communications (Ofcom).

2004 additional number ranges within existing ELNS areas

In 2004, Ofcom allocated the remaining number ranges within the 14 existing ELNS areas.

2004 additional number ranges within existing mixed areas

In 2004, Ofcom allocated the remaining number ranges within the existing 18 "mixed" areas.

2004 introduction of 056 VoIP numbers

In 2004, Ofcom started allocating 056 numbers for VoIP services. Soon after, VoIP services also appeared on geographic 01 and 02 numbers. Uptake of 056 numbers remains low. These numbers have 10 digits.

2005 to present day: new allocations within existing 02x areas

These are detailed as extra entries within the Big Number Change section above.

2005 removal of unused 09xx broadband services from number plan

Some years earlier, 092x to 099x had been designated "broadband services". With changes in technology, this allocation had never been used. It was removed from the plan in 2005.

2005 adult premium rate services begin using 098x numbers

With calls for premium rate adult services to be more clearly defined and separated from other premium rate services, the 0908 and 0909 codes were to be no longer issued for new services. Instead, the new 098x range would be used, initially 0982 but latterly also 0983, 0984 and 0989.

Some companies had attempted to avoid restrictions placed on Premium Rate Services by instead running adult services on various 070, 0871 and other number ranges. Regulations were eventually drafted to force these services to use only the designated 098x (and pre-existing 0908 and 0909) numbers.

2005 NHS banned from using 0870 and 09xx numbers

Due to concerns raised by patients having to pay unfair costs when calling NHS services by telephone, the usage of 0870 non-geographic numbers was banned by the Department of Health in 2005. At that time, 0870 numbers often cost more to call than geographic 01 and 02 numbers and were not usually included in bundled minutes. Around 400 GP surgeries used 0870 numbers and were also coming under greater scrutiny with a few reverting to geographic numbers.

Many of these services quickly moved to 0845 or 0844 revenue share numbers as they were not specifically banned, even though they also cost more to call than 01 and 02 numbers and in many cases cost more to call than 0870 numbers. The tendency to unlawfully refer to 084x numbers as 'local rate' or 'lo-call' numbers hid the true cost of calling them, compared to the price for calling geographic numbers. One supplier of surgery telephone systems opted to use 0844 revenue share numbers paying the surgery 2p/min from the 5p/min "premium" paid by callers. Contravening ASA advice, surgeries were told that 0844 numbers were "lo-call" numbers and subsequent tariff comparisons ignored both packages with inclusive minutes and users with mobile phones.

In December 2006, Lord Norman Warner sent a letter to all Primary Care Trust Chief Executives drawing attention to the Central Office of Information guidance on telephone numbering, which suggested that healthcare providers consider adopting an 03 telephone number so that people "do not have to pay over the odds to contact their local services". Very few took notice. In July and November 2007, two Early Day Motions were signed by numerous MPs calling for GPs to no longer use 0844 and other such expensive telephone numbers.

In recent years, there has been much discussion in the media about the use of 0844 numbers in the healthcare sector, mainly due to the costs incurred by people who have to dial these numbers as the primary form of contact with their local healthcare services, especially when calling from mobiles.

The issue was debated in Parliament in early 2008. The BMA recommended that GPs publish call costs for 0844 numbers in surgeries. Former Health Secretary Alan Johnson has publicly advocated the use of 03 numbers. By early 2008 there were already more than 800 GPs in England using 0844 telephone numbers.

The Department of Health started investigating the use of 084 numbers in the NHS in March 2008 Phone supplier NEG stated their belief that 0844 numbers would not be banned.

In 2008, Leicester City NHS Trust looked into their usage of telephone numbers and revealed a complex set of issues to be solved, some of which were fixed later in the year. Enfield Primary Care Trust wrote to all 62 surgeries in the borough warning them that it does not approve of them using premium rate 0844 numbers. It was revealed that Mid-Yorkshire hospital trust had made more than £80,000 from use of a 0844 telephone number in two years. By late 2008, the number of GPs surgeries using 084 numbers had risen to 1500.

The Department of Health published a consultation at the end of 2008 calling for views on the usage of 084 numbers in the NHS which received more than 3000 responses. In response, the British Medical Association (BMA) stated "GP practices using 084 telephone numbers must be allowed to serve out the terms of their contracts with telephone suppliers if the government decides to ban them from the NHS," as many had already mistakenly signed up to long contracts for 0844 numbers. Ofcom recommended the 03 option. In 2009, Heart of Birmingham Primary Care Trust moved 22 GPs to new 0345 numbers.

Although 0870 numbers were banned in 2005, even as late as 2010 there were NHS bodies only now just getting around to complying with that ban.

2006 ASA start taking action against misleading price indications for 084 and 087 numbers

In 2006, the Advertising Standards Authority (ASA) started taking action against companies that falsely represent that "084 numbers are 'local rate' [sic] or 'lo-call' [sic] calls" or "087 numbers are 'national rate' [sic] calls". By this time, most operators no longer offered a "local call" rate, instead charging all calls to 01 and 02 numbers at the same rate, whatever the distance.

After 2005, several operators also offered 01, 02 and the newly created 03 numbers as "free minutes" within an "evening and weekend" calls bundle or within an "anytime" calls bundle. As 084 and 087 numbers were not usually included in any such bundle, costing up to 20p/min from landlines and up to 41p/min from mobiles, describing these numbers as anything other than "chargeable with an additional service charge" (or "premium" by another name) is a misleading price indication. In comparison, for many callers, calls to 01, 02 and 03 numbers had effectively become "free".

2006 new 075xx mobile numbers introduced

As a result of ever increasing mobile phone ownership, and especially the introduction of mobile broadband in the UK, the 075xx number range was opened in October 2006. This joined the existing 07624, 077xx, 078xx and 079xx ranges.

2006 introduction of 101 for non-emergency calls to the police

In 2006, the new 101 number for non-emergency calls to the police began trials in several areas with a call cost of 10 pence per call. The number was adopted nationally in 2011/2012. Calls now cost 15 pence per call from landlines and mobiles.

2007 introduction of 03 non-geographic numbers

In February 2007, Ofcom announced the 03 range of numbers was being brought into use and the first numbers were issued in May. Although allocated as non-geographic, these were to be charged at the same rate as geographic 01 and 02 numbers from both landline and mobile and were also to be included within "free minutes" bundles for subscribers with a call package. Further details are in the 03 numbers section above.

2007 new 0843 and 0872 non-geographic revenue-share numbers

In May 2007, Ofcom allocated the first 0872 numbers. These follow on from the earlier 0871 code which was now fully allocated.

In November 2007, the first 0843 numbers were allocated. These follow on from the earlier, and now fully allocated, 0844 code.

These are used for revenue share services and are generally not included in bundled minutes from either mobiles or landlines. From landlines these numbers cost anything up to 20 pence per minute and from mobile phones anything up to 45 pence per minute. The price includes a revenue-share "premium" or "service charge" of up to 5 pence per minute for 0843 numbers and up to 10 pence per minute for 0872 numbers. The premium is passed on to the terminating telecoms company.

Ofcom also indicated that 0842 and 0873 will follow on from these allocations at a later date.

Due to continued misuse of the 0871 and 0872 number ranges, ICSTIS consulted on additional regulation in 2006 and announced in 2007 that both number ranges were to be regulated from 2008. After some delay they were eventually taken into the jurisdiction of PhonepayPlus in 2009. PhonepayPlus replaced ICSTIS in 2007.

2008 new area code: 01987 Ebbsfleet

In 2008, a new area code was created for Ebbsfleet. Adjacent area codes no longer had enough projected spare capacity for the new development to use, so 01987 was allocated.

2009 Reform of 070 personal numbering

Ofcom had previously considered that personal numbers should migrate to 06, to replace the 070 prefix that is sometimes confused with mobile phone numbers. There is no cap on retail caller charges. Ofcom wanted 070 and 06 numbers to have a price cap, and 07 numbers to be used exclusively for mobile phones.

Companies such as Hospedia (formerly Patientline) use 070 personal numbers. After an in-depth study to better understand the market, Ofcom has changed its mind and is now proposing to drop the 060 migration concept and decided that the forced migration to 060 is no longer seen to be objectively justifiable. Premium rate and other such services were also banned from using 070 numbers.

2009 introduction of 116 xxx numbers

In 2009, Ofcom introduced the first harmonised European numbers for harmonised services of social value, and additional numbers were allocated in 2010.

2009 new 074xx mobile numbers introduced

As a result of ever increasing mobile phone and mobile broadband ownership, the 074xx number range was opened in July 2009. This joined the existing 075xx, 07624, 077xx, 078xx and 079xx ranges.

2009 revenue-share no longer allowed on 0870 non-geographic (and 070 personal) numbers

After a sustained period of abuse, revenue share was removed from 0870 and 070 numbers. Prices for calling 0870 numbers from landlines fell and some landline providers started to allow calls to 0870 numbers to appear within call-plan inclusive minutes. Revenue-share continued on 0843, 0844, 0845, 0871 and 0872 numbers.

It was anticipated that 0845 numbers would also lose their revenue share, leading BT to prematurely include these numbers within call plans. Ofcom changed their mind and the status of 0845 numbers wasn't changed. Instead, in 2010 to 2012, Ofcom eventually consulted on re-organisation of the whole of the 084 and 087 number ranges.

2009 PhonepayPlus begins regulation of 0871 and 0872 numbers

After ICSTIS consultation in 2006 and 2007 numbers beginning 0871 (and 0872) began to be regulated by PhonepayPlus, the premium rate services regulator from 1 August 2009. This brings regulation in line with existing 09xx premium rate services, 070 personal numbers and 118 xxx directory enquiries. ICSTIS became PhonepayPlus on 15 October 2007. 0871 and 0872 numbers retained their revenue-share status.

2010 GPs banned from using 0844 (and other 084x and 087x) numbers

It had been widely reported in 2009 that 084 numbers were to be banned from the NHS. In December 2009, the Department of Health published directions to NHS bodies concerning the cost of telephone calls made by patients to the NHS: "An NHS body must not enter into, renew or extend a contract or other arrangement for telephone services unless it is satisfied that, having regard to the arrangement as a whole, persons will not pay more to make relevant calls to the NHS body then they would to make equivalent calls to a geographic number." This reiterated the "free at the point of delivery" principle of the NHS and the direction applied to all NHS bodies.

The accompanying letter introduced ambiguity: "These Directions do not prohibit an organisation from using specific number ranges for the purpose of contacting NHS services. Organisations remain free to use non-geographical number ranges such as 084, providing that patients are not charged more than the equivalent cost of calling a geographical number to do so." Simple inspection of the call price lists for all major landline and mobile telephone service providers readily confirmed that 0844 numbers always cost more than 01 and 02 numbers. From this, it is clear that only 01, 02 and 03 numbers can be used by NHS bodies.

0844 numbers continued to be adopted by GPs, with an estimated 200 more signing up in the final six months of 2009.

The GP committee of the BMA (British Medical Association) advised that NEG (Network Europe Group, a supplier of telephone switchboard equipment to GPs and a reseller of the telephone lines and numbers that GPs use) had assured both the BMA and the Department of Health that 0844 numbers were "local rate" calls charged at rates less than geographic calls, and that GPs could continue using them as long as each GP obtained that assurance from NEG. However, NEG does not have any patients as customers nor does NEG set the prices for calls that patients make, nor does it send out bills to patients, so any such assurance is worthless. Patients are billed by BT, Sky, Virgin, Vodafone, O2, Orange, T-Mobile, and others, and all of those charge more for calling 0844 numbers than for calling 01, 02 and 03 numbers.

With widespread abuse of non-geographic numbers continuing unabated, Ofcom started a long series of consulatations in April 2010. Also in April 2010, the Department of Health introduced new GMS (General Medical Services) contracts so that GPs would now also be covered by the earlier direction. From this point on, the more than 6500 GP surgeries in England and Wales were banned from using phone numbers that "cost more than calling a geographic number", and given one year to comply. The GMS contract variation was needed as GPs are not NHS bodies, rather independent contractors.

Questions were asked in the Scottish Parliament in June 2010.

In a move out of step with other changes, plans for the existing NHS Direct 0845 46 47 number to migrate to a cheaper-to-call 03 number were scrapped as plans for a new 111 service were already well advanced.

A year after the GMS contract variation came into effect, many GPs were continuing to use 0844 numbers in defiance of the ban. In March and May 2011, more than 1300 GP surgeries were still using the banned 0844 (and 0845/0870) numbers. It was becoming clear that local decision makers (i.e. PCTs and GPs) had failed to understand the 0844 revenue share mechanism as well as the price regulations that apply uniquely to BT and make their call rates atypical when compared to other providers. At least one PCT claimed that they did not know what patients were paying for calls and further claimed that they had no way of finding out, seemingly unaware that every telecoms supplier publishes a detailed price list on their respective websites.

NEG continued to issue a revised version of their "letter of compliance", assuring GPs that calling 0844 numbers does not cost more than calling 01 and 02 numbers and in May 2011 issued a much longer document in response to earlier Daily Mail articles that had exposed the differences between the position taken by NEG and the actual provisions laid out in the April 2010 GMS contract variation. In July 2011, the BMA advocated that GPs should only consider the call costs for patients calling from BT (British Telecommunications PLC) landlines using tariffs without "inclusive" call allowances. The BMA advised that GPs should not consider the price of calls for patients calling from landlines other than BT, nor those with inclusive allowances or using mobile phones. This advice directly contradicted the statement recently made in Parliament: "It is absolutely clear that there is no distinction between landlines, mobiles or payphones. The directions are very clear that patients should not expect to be charged any more."

PCTs (Primary Care Trusts), en masse, had seemingly misunderstood the regulations or had been misled by the incorrect advice spread by NEG and the BMA as by November 2011 more than 1400 GPs were using the "banned" numbers.

Protests against the use of 0844 numbers were growing. There are even cases of GPs changing to 0844 numbers a year after the ban started.

Only a small number of GPs had complied with the ban. Various GPs using 0844 numbers attempted to justify their position based on demonstratably false information. In some areas, patients took it upon themselves to find and publish geographic numbers for GPs continuing to flout the 0844 ban.

In January 2012, a parliamentary debate took place where it was confirmed that users "should not pay more than a geographic rate call" and it was clarified that this applies to "both landlines and mobiles". Additionally, "bundled" or "free minutes" should also count. The reference provides some additional commentary on the major points.

A month later, the Department of Health issued further guidance on the use of 084 numbers in the NHS confirming that GPs should consider "all means of telephoning the practice – including from payphones, mobile phones and landlines" which the BMA disputed. 0844 numbers were mentioned again in a parliamentary debate in March 2012 when the Secretary of State Andrew Lansley confirmed: "We have made it very clear that GPs should not be using 0844 numbers for that purpose and charging patients for them." A small number of surgeries have since complied with the regulation by moving to 01 or 02 numbers but most have not done so. In 2012, NEG issued several revised documents claiming compliance using non-typical tariffs as a basis for comparison and ignoring bundled minutes and again in 2013.

The Northern Ireland Assembly debated the issue in May 2012 where it was disclosed that 23 of Northern Ireland's 355 GP surgeries use an 0844 number. A briefing note was produced within, and for the usage of, UK government. This covered some of the history relating to the issue. Campaigners had already produced a simplified timeline. In their response to an ongoing Ofcom consultation on simplifying non-geographic numbers, NEG said "Under the proposed new structure, Ofcom expects call cost descriptions to follow the format: 'This call will cost you X pence per minute plus your phone company's access charge.' We do not believe that it is appropriate for a patient to receive the Service Charge information advised by OFCOM when they contact their surgery as this will only seek to alarm them, and perpetuate the myth that all calls (to 084 numbers) are more costly."

In order to comply, GPs should be using numbers that begin 01, 02 or 03 and should not be using numbers that begin 070, 084, 087 or 09. The 034 and 037 ranges are reserved specifically for 084 and 087 migration. GPs using 084 and 087 numbers can migrate to the equivalent 034 or 037 version of their number without ending their phone service contracts. Alternatively they can move to brand new 030 or 033 numbers or to a geographic 01 or 02 number. Only a few GPs and NHS services have chosen 03 numbers even though this should be the most obvious solution since 03 numbers allow the same call queueing and call management facilities as 084 and 087 numbers while costing the same as 01 and 02 numbers for all callers.

In spite of the ban on 0844 numbers in the NHS since April 2010, more GPs continue to sign up to use them however PhonepayPlus has also taken an interest in extending regulations that already cover 09 and 087 numbers — as used for premium rate chat lines, competitions and phone-in voting systems — to also cover 084 numbers.

Multiple PCTs have failed to enforce the terms of the April 2010 variations to the GMS contract and many GPs continue to use the banned numbers. At least one surgery with an 0844 contract and with considerable time remaining time before it ends has adopted Skype as an alternative method of contacting the surgery. Some surgeries have two telephone numbers: one a premium rate 0844 number with a higher level of service and the other a standard geographic 01 or 02 number with a lower level of service, thereby creating a two-tier system for accessing the NHS services.

Almost three years after the ban, some GPs within the constituencies of government ministers continue to use 0844 numbers. In the South-East of England, usage of 0844 numbers continues unabated. In any case, in 2013 the Consumer Rights Directive will soon make it illegal to use 084 and 087 numbers, indeed any number that "costs more than geographic rate", for customer services and complaints. Where contracts are ending, GPs often choose to return to using 01 and 02 numbers even though 03 numbers cost the same for all callers.

2010 introduction of 111 for non-emergency calls to NHS

In 2010, 111 was introduced on a trial basis for non-urgent calls to the NHS. The scheme is planned to roll out nationally in 2013 and at that time may replace the currect NHS Direct 0845 46 47 line (in England and Wales) and the NHS 24 08454 24 24 24 line (in Scotland).

2010 additional number ranges within 0191 area code

Extra capacity assigned in late 2010, following consultation.

In the other 01x1 area codes, only (0121) 8xx, (0121) 9xx, (0131) 9xx and (0161) 5xx have yet to be allocated. 0171 and 0181 are no longer in use and 0101 and 0111 have never been allocated.

2010 Ofcom propose changes in number conservation areas

In November 2010, Ofcom proposed to abandon renumbering in areas running short of capacity and instead provide extra capacity by starting to use local numbers beginning '0' and '1', and removing the option of dialling locally using just the subscriber number. Once the supply of new numbers released by this measure is exhausted Ofcom propose introducing additional, overlay area codes to run in tandem with current codes. It is anticipated that the overlay codes would not be required before 2022.

2011 area name changes

By way of an Erratum to the National Telephone Numbering Plan, Ofcom started the lengthy process of correcting some very old errors for nine area code names in December 2011.

Some of these errors first appeared in the 2003 version of the number plan while others can also be found in older data originally produced by Oftel several years before.

As noted on Ofcom's site, the name changes still have to go through a formal consultation process, even though they are only correcting obvious spelling, hyphenation and capitalisation mistakes.

The corrections are as follows:

2012 changes in local dialling

In November 2012, local dialling was removed for calls within the 01202 area allowing subscriber numbers beginning 0 or 1 to be issued locally and buying more time before an additional area code or code change is required.

2013 changes in 080, 084 and 087 non-geographic arrangements

After initial consultation in 2010 and 2012, in April 2013 Ofcom published the final consultation on proposals to re-arrange the 080, 084 and 087 non-geographic allocations in 2014.

The 0870 range is to regain its revenue share status. Where users of 0870 numbers cannot justify revenue share they are advised to move to their reserved matching 0370 number. The workings of the 0845 range will broadly align with how 0844 and 0843 revenue share numbers already work.

Changes in how call costs for 084 and 087 non-geographic calls should in future be communicated to callers were announced. The callers phone line provider has to list a single Access Charge per tariff for the 084, 087, 09 and 118 non-geographic number ranges and the called party has to display the single Service Charge (or "premium") details for their non-geographic number.

Calls to the 'free to caller' 080 range will be made free from mobile telephones, not just from landlines.

Once the final announcements are made by Ofcom in the summer of 2013, the changes will have an 18-month transition period before coming into effect.

2014 local number dialing

In October 2014 certain area codes required the full area code even when dialing local numbers. The areas affected were:

Aberdeen (01224)

Bradford (01274)

Brighton (01273)

Middlesbrough (01642)

Milton Keynes (01908)

The change was in response to a lack of free numbers in these areas. By requiring the area code for all local calls, Ofcom are able to allocate numbers starting with 1 or 0. This increases the number of telephone numbers available without requiring a number change.

2015 UK Calling legislation

On 1 July 2015, Ofcom made a number of changes to the way phone calls to UK service numbers would be charged. The cost of calls made to service numbers is now split into two parts: an access charge and a service charge. Under the new legislation, which was promoted by an information campaign entitled UK Calling, call charges must be clearly stated on all materials that advertise a service number. The 1 July changes also saw ‘freephone numbers’ 0800 and 0808 become free to call from both mobiles and landlines. Meanwhile, 0500 numbers remain chargeable as previously from mobiles (free from landlines, also as previously). Plans are afoot to migrate these to 08085 numbers in mid-2017, whereupon they will become free from mobiles.

ELNS areas

Area codes for mobile phone, local rate, premium rate and other such special numbers originally used ordinary looking area codes in the 02xx to 09xx range. In the early 1980s only a few such codes were in use. Rapid expansion of these services in the late 1980s required many new codes, but there were a diminishing number of codes available for use. In order to free up space for these services, 30 geographic ABC area codes with low number use were condensed into 14 ABC ranges such that each numeric area code would cover multiple charge groups (these migration figures do not include the similar 091 area code changes).

Numbers in Barrow-in-Furness already used (0229) 2 and (0229) 5. Millom used the separate 0657 area code. Millom numbers were transferred to the 0229 area code. Millom numbers would begin (0229) 3 and (0229) 7 and have 6 digits.

Under the new "ELNS" (Extended Linked Numbering Scheme) arrangement, two charge groups now share the same area code and the leading digit of the local number indicates which charge group the number belongs to. The new area code retains both of the old area code names. A diagram showing the principle is shown on page 9 of Oftel's telephone numbering guide and these areas are shown in the table below. Some ELNS areas combined three charge groups. Calls within the area code do not require the area code to be dialled, this is true even for calls between the charge groups.

Of the 16 area codes freed up for alternative use in the 1980s, at least 11 were re-used for other services. For example, the 0401 area code was re-allocated to Cellnet mobile services. Five of the area codes remained unused. In 1995, the PhONEday changes for geographic numbers solved the number shortage problem for mobile and non-geographic services by freeing up the whole 07, 08 and 09 range for their use from 2000 onwards.

On PhONEday in 1995, 0229 became 01229 and 0964 became 01964 and these codes are still in use today. The remainder of the "ELNS" area code allocations and their history are detailed in the table below.

The Cellnet mobile 0401 allocation stayed in use for about a decade before these numbers were transferred to the 07701 range in the Big Number Change in 2000. Nowadays all 16 of the area codes freed up in the 1980s (albeit now with a 1 prefix, e.g. 0401 is now 01401) remain unused and are available for future geographic expansion.

Mixed areas

Area codes for mobile phone, local rate, premium rate and other such special numbers originally used ordinary looking area codes in the 02xx to 09xx range. In the early 1980s only a few such codes were in use. Rapid expansion of these services in the late 1980s required many new codes, but there were a diminishing number of codes available for use. In order to free up space for these services, 17 geographic ABC area codes with low number use were condensed into 6 ABC ranges under a "mixed" scheme.

Numbers in Dumfries already used (0387) 2 and (0387) 5. Numbers in Langholm were 4 or 5 digits long and used the 0541 area code. Langholm numbers were changed to 5 digits and transferred to the newly created 03873 area code.

Under the new "mixed" arrangement, although 0387 and 03873 shared the same ABC digits, they were treated as completely separate area codes. All calls from one area to the other require the area code to be dialled. Local numbers in Dumfries cannot begin with a "3".

Of the 11 area codes freed up for alternative use in the 1980s, only 5 were actually re-used for other services. For example, the 0541 area code was re-allocated to C&WC Area Call services. Six of the area codes remained unused. In 1995, the PhONEday changes for geographic numbers solved the number shortage problem for mobile and non-geographic services by freeing up the whole 07, 08 and 09 range for their use from 2000 onwards.

On PhONEday in 1995, 0387 became 01387 and 03873 became 013873 and these codes are still in use today. The remainder of the "mixed" area code allocations and their history are detailed in the table below.

The C&WC 0541 allocation stayed in use for more than a decade before these numbers were transferred to the 0870 1 range in the Big Number Change in 2000. Nowadays all 11 of the area codes freed up in the 1980s (albeit now with a 1 prefix, e.g. 0541 is now 01541) remain unused and are available for future geographic expansion.

NHS direct

The short number 0845 1888 was set aside in March 1998 for trials of the new NHS direct service with calls charged at the "local rate". At a later date, the number was changed to 0845 46 47.

Warnings from Oftel

After the migration of geographic 0xxx area codes to new 01xxx codes on PhONEday (also 0xx → 01xx and 0xxxx → 01xxxx of course), some of the old area codes had started to be re-used for other purposes. For example, 0870 (Isle of Benbecula, Outer Hebrides) had been moved to 01870 and now 0870 started to be re-used for non-geographic services. Oftel had to issue a warning to operators to remove their "this number has changed, please redial inserting a one after the initial zero" messages that had been applied on PhONEday so that callers could get through to the new non-geographic numbers.

Premium rate and mobile problems

With the diverse usage and pricing of similar looking codes there could easily be a nasty shock when the bill arrived. Office phone systems could be set to block various premium rate prefixes, but it was important to regularly review and update the list. For those that did not, problems accessing some numbers were beginning to develop. The 0930 code was mainly used for premium rate services, but 0930 7xxxxx was used by One2One for mobile telephone services. Some people found that calls to all 0930 numbers were barred and hence also those mobile phones. To overcome this, the 0961 7xxxxx range was mirrored on to 0930 7xxxxx. These were all 9-digit numbers.

New premium rate services start using 090x

From 1998 onwards, 090x numbers with 10 digits started coming into use for premium rate services. As with 084 and 087 numbers, certain small number blocks within the 090x range were set aside for migration of old premium rate codes in the forthcoming Big Number Change.

The 09 number range was originally subdivided as follows:

From 23 August 1999, Oftel added the 0905 range as by then 0906 was almost fully allocated.

Internet for schools

Announced in November 1997 and issued from February 1998 onwards the 0820 range was designated "internet for schools".

Number conservation

As the number of lines in use continued to grow, some areas became close to full capacity. In the late-1990s, Ofcom signalled a number of areas of concern.

Of these, only Coventry was immediately addressed - by migration to the 024 code and eight digit subscriber numbers in the Big Number Change in 2000. The Bournemouth, Aberdeen, Brighton, Bradford and Middlesbrough (as well as Milton Keynes, despite not being initially highlighted in the report) areas were later addressed in 2012 and 2014 by requiring 11-digit dialling for local calls (see the 2012 and 2014 local number dialling sections below), as an interim measure until shorter area codes and 8 digit local numbers are introduced.

Broadband services

The 092x to 099x range was designated "broadband services".

The allocation was never used and eventually removed from the plan in 2005.

Local dialling short codes

Calls between nearby exchanges could previously be dialled using a "short code", often beginning 7, 8 or 9. With rising demand for more subscriber numbers, these codes were scrapped in the late 1990s. After a short delay, 6-digit subscriber numbers beginning 7 or 8 began to be issued in these 01xxx areas, and with 5-digits in 01xxxx areas. In the mid- and late -2000s, some of these areas also started issuing subscriber numbers beginning 9.

Geographic numbers

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).

Although Southampton and Portsmouth are one code from a code structure and local dialling point of view, calls between them are not treated as local calls for pricing purposes.

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.

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.

Non-geographic, and mobile and pager numbers

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) 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

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", "0208" and even "0203", which was the pre-1995 code for Coventry). 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.

Misconceptions

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 and (024) 75xx 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 and (029) 22xx 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).

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, even now, some twelve 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). This is a particular problem now that (0114) 3xx xxxx local numbers are being issued.

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.

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.