Big Number Change
The Big Number Change addressed various issues with the telephone dialling plan in the United Kingdom, during the late-1990s and early-2000s.
The first was an update to a small number of geographic dialling codes in response to the rapid late-1990s growth of telecommunications and impending exhaustion of local numbers in several cities. The change greatly expanded the pool of available numbers within those places while retaining 'local dialling'. The change affected the dialling codes assigned to Cardiff, Coventry, London, Northern Ireland, Portsmouth and Southampton, culminating in a large switch on 22 April 2000. All of these places moved to eight-digit local numbers ensuring sufficient local capacity for many decades. No other geographic area codes were affected.
The other set of changes affected mobile, non-geographic and premium rate numbers, completing a series of steps first detailed almost a decade earlier. In the early-1990s, mobile, non-geographic and premium rate services had used nine digit numbers with various codes such as 0402, 0645, and 0898 scattered among the similar-looking geographic area codes such as 0384, 0562 and 0949. The number of available codes for new services was quickly dwindling. In 1995, PhONEday partially addressed this by altering all geographic area codes to begin 01, freeing up hundreds of codes beginning 02 to 09 for other uses. Existing mobile, non-geographic and premium rate services continued as before, using various codes from 02 to 09 and with nine-digit numbers.
In 1997 and 1998, mobile, non-geographic and premium rate numbers started to be issued with ten digits and using only specific new prefixes: 070 for personal numbers, 076 for pagers, 077xx, 078xx and 079xx for mobiles, 0800 and 0808 for freephone, 0845 and 0870 for non-geographic revenue-share numbers and 090x for premium rate numbers. Within each of these groups some smaller number blocks were held aside for the older 9-digit mobile, non-geographic and premium rate services to move into at a later date. In 2000 and 2001, the Big Number Change put those final parts into place and they are detailed below.
At the end of the process, there were no numbers in the UK beginning 03, 04 or 06. Additionally, the 02, 05, 07, 08 and 09 ranges were only lightly used. With PhONEday in 1995 and the Big Number Change, the UK had achieved huge spare capacity for new services and simple to understand prefix groupings: 01 and 02 for geographic numbers, 070 for personal numbers, 076 for pagers, 07624, 077, 078 and 079 for mobiles, 0500 and 080 for freephone, 084 and 087 for non-geographic and 090 for premium rate. Further new allocations would initially conform only to those groupings. Over the following decade, the 030, 033, 034, 037, 055, 056, 074, 075, 091 and 098 ranges would also come into use for new services or for further expansion of old services.
Geographic number changes
These changes set the following areas to use 02 area codes and eight-digit subscriber numbers.Great Britain
Note Under the change, the two London areas were reunified under the single code. New numbers beginning with 7, 8 or 3 were allocated regardless of location.All of the above areas now have an eight-digit local number, in place of their previous six or seven-digit local number. For a short while, you could use either number for local dialling, but local access to the old, shorter numbers was switched off after a few months of parallel running.
Within London, new 70xx xxxx, 71xx xxxx, 80xx xxxx and 81xx xxxx numbers became available for general use. These began to be allocated anywhere in London, with no regard for the 1990-2000 inner/outer London geographical split.
In all of the other areas, new BC0x xxxx and BC1x xxxx numbers became available for general use at the same time.
Northern Ireland
In Northern Ireland, the situation was more complicated. While the primary reason for the changes was the lack of numbering capacity in Belfast, this was not the only reason. When STD codes were introduced in the 1950s, Northern Ireland was allocated only 14 area codes for 34 charging groups. Normal practice in Great Britain was to allocate one area code per charging group but, as calls to Northern Ireland were national rate from anywhere in GB, it was not seen to be necessary to differentiate between all of them. So, area codes covering multiple charge groups were created; in practice this meant that some areas had longer area codes. For example, while Enniskillen was allocated the area code 0365, Kesh was allocated 03656 and Lisnaskea 03657. As a result, numbers in Enniskillen could not begin with 6 or 7, as this would conflict with those of Kesh or Lisnaskea.All this meant that while Enniskillen's numbers could be six digits long, Kesh's and Lisnaskea's could only be five digits, due to the 9-digit limit of the length of a phone number at the time. This severely restricted capacity in these areas. As a result, at the Big Number Change, all these dependent exchanges were migrated to different numbers than their parent exchanges; in this instance while Enniskillen's 01365 was migrated to 028 66, Kesh went from 013656 to 028 686 and Lisnaskea from 013657 to 028 677. This meant that Kesh could expand into the rest of the 028 68xx range.
Note that the new numbering scheme groups numbers together such that the first digit identifies the county in alphabetical order. The exception is the Greater Belfast area where all numbers begin with 9, regardless of the county. The full list of changes for Northern Ireland is as in the table above.
National dialling only ranges
In London, old National Dialling Only 0xx xxxx and 1xx xxxx numbers were migrated to new 0axx xxxx and 1axx xxxx numbers.In all of the other areas, old National Dialling Only 0xxxxx and 1xxxxx numbers were migrated to new 0aax xxxx and 1aax xxxx numbers.
The migration from old to new numbers was as follows:
| Area | Old range | New range |
| Coventry | 01203 0xxxxx | 024 010x xxxx |
| Coventry | 01203 1xxxxx | 024 111x xxxx |
| Cardiff | 01222 0xxxxx | 029 010x xxxx |
| Cardiff | 01222 1xxxxx | 029 111x xxxx |
| Belfast | 01232 0xxxxx | 028 010x xxxx |
| Belfast | 01232 1xxxxx | 028 101x xxxx |
| Southampton | 01703 0xxxxx | 023 010x xxxx |
| Southampton | 01703 1xxxxx | 023 111x xxxx |
| Portsmouth | 01705 0xxxxx | 023 010x xxxx |
| Portsmouth | 01705 1xxxxx | 023 101x xxxx |
| London | 0171-0xx xxxx | 020 01xx xxxx |
| London | 0171-1xx xxxx | 020 11xx xxxx |
| London | 0181-0xx xxxx | 020 00xx xxxx |
| London | 0181-1xx xxxx | 020 10xx xxxx |
Non-geographic number changes
Special services and freephone
The following changes were made to non-geographic numbering ranges to bring them in the 08xx special services range.| Code | Charging rate | Before BNC | After BNC |
| 0345 | Local rate | 0345 xxxxxx | 0845 7xx xxxx |
| 0645 | Local rate | 0645 xxxxxx | 0845 9xx xxxx |
| 0374 5 | National rate | 0374 5xxxxx | 0870 45x xxxx |
| 0541 5 | National rate | 0541 5xxxxx | 0870 15x xxxx |
| 0990 | National rate | 0990 xxxxxx | 0870 5xx xxxx |
| 0321 | Vodafone Freephone | 0321 xxxxxx | 0808 0xx xxxx |
| 0500 | Mercury Freephone | 0500 xxxxxx | no change |
| 0800 | BT Freephone | 0800 xxxxxx | no change |
The 0500 code remained in use after The Big Number Change, but no new numbers were allocated after 28 April 2001. The 0500 range was eventually ceased on 3 June 2017, with numbers transferred to 0808 5xx xxxx equivalents during a three year transition period prior to that date.
The 0800 code has remained, but no new nine digit numbers have been allocated since 1997. Instead, all 0800 numbers issued since that time have ten digits after the leading 0 or +44.
Premium rate
The following changes were made to non-geographic numbering ranges to bring them in the 090x premium rate range.| Code | Charging rate | Before BNC | After BNC |
| 0331 | VoData premium rate | 0331 | Unknown |
| 0336 0 | VoData premium rate | 0336 0xxxxx | Unknown |
| 0336 1 | VoData premium rate | 0336 1xxxxx | Unknown |
| 0336 2 | VoData premium rate | 0336 2xxxxx | Unknown |
| 0336 3 | VoData premium rate | 0336 3xxxxx | Unknown |
| 0336 4 | VoData premium rate | 0336 4xxxxx | Unknown |
| 0336 5 | VoData premium rate | 0336 5xxxxx | Unknown |
| 0336 6 | VoData premium rate | 0336 6xxxxx | Unknown |
| 0336 8 | VoData premium rate | 0336 8xxxxx | Unknown |
| 0336 9 | VoData premium rate | 0336 9xxxxx | Unknown |
| 0338 | Mercury premium rate | 0338 | Unknown |
| 0632 | Premium rate | 0632 xxxxxx | 090x |
| 0640 | Mercury premium rate | 0640 | 090x |
| 0660 | Mercury premium rate | 0660 xxxxxx | 090x |
| 0696 | Premium rate | 0696 xxxxxx | 090x |
| 0696 6 | Jersey Telecoms premium rate | 0696 6xxxxx | 090x |
| 0696 8 | Manx Telecoms premium rate | 0696 8xxxxx | 090x |
| 0696 9 | Guernsey Telecoms premium rate | 0696 9xxxxx | 090x |
| 0836 | premium rate? | 0836 | |
| 0839 | Mercury premium rate? | 0839 xxxxxx | Unknown |
| 0853 | Premium rate | 0853 | 090x |
| 0881 1 | Mercury premium rate | 0881 1xxxxx | 090x |
| 0881 2 | Mercury premium rate | 0881 2xxxxx | 090x |
| 0881 3 | Mercury premium rate | 0881 3xxxxx | 090x |
| 0881 5 | Mercury premium rate | 0881 5xxxxx | 090x |
| 0881 6 | Mercury premium rate | 0881 6xxxxx | 090x |
| 0881 7 | Mercury premium rate | 0881 7xxxxx | 090x |
| 0881 9 | Mercury premium rate | 0881 9xxxxx | 090x |
| 0890 | Premium rate | 0890 xxxxxx | 090x |
| 0891 | BT ValueCall | 0891 xxxxxx | 090x |
| 0894 | BT premium rate | 0894 | 090x |
| 0895 | premium rate? | 0895 | |
| 0896 | Premium rate | 0896 | 090x |
| 0897 | BT premium rate | 0897 | 090x |
| 0898 | BT premium rate | 0898 xxxxxx | 090x |
| 0930 0 | Premium rate | 0930 0xxxxx | 090x |
| 0930 1 | Premium rate | 0930 1xxxxx | 090x |
| 0930 2 | Premium rate | 0930 2xxxxx | 090x |
| 0930 3 | Premium rate | 0930 3xxxxx | 090x |
| 0930 4 | Premium rate | 0930 4xxxxx | 090x |
| 0930 5 | Premium rate | 0930 5xxxxx | 090x |
| 0930 6 | Premium rate | 0930 6xxxxx | 090x |
| 0930 8 | Premium rate | 0930 8xxxxx | 090x |
| 0930 9 | Premium rate | 0930 9xxxxx | 090x |
| 0991 | Mercury premium rate | 0991 | 090x |
Mobile, pager and personal number changes
Personal numbers
moved to the 070 range.| Code | Charging rate | Before BNC | After BNC |
| 0956 7 | FleXtel Personal Numbering | 0956 7xxxxx | 070 107x xxxx |
Mobile numbers
The following changes were made to mobile phone numbering ranges to bring them in the 07xxx mobile numbers range.| Code | Operator | Before BNC | After BNC |
| 0370 | Vodafone | 0370 xxxxxx | 07770 xxxxxx |
| 0374 0 | Vodafone | 0374 0xxxxx | 07774 0xxxxx |
| 0374 1 | Vodafone | 0374 1xxxxx | 07774 1xxxxx |
| 0374 2 | Vodafone | 0374 2xxxxx | 07774 2xxxxx |
| 0374 3 | Vodafone | 0374 3xxxxx | 07774 3xxxxx |
| 0374 4 | Vodafone | 0374 4xxxxx | 07774 4xxxxx |
| 0374 6 | Vodafone | 0374 6xxxxx | 07774 6xxxxx |
| 0374 7 | Vodafone | 0374 7xxxxx | 07774 7xxxxx |
| 0374 8 | Vodafone | 0374 8xxxxx | 07774 8xxxxx |
| 0374 9 | Vodafone | 0374 9xxxxx | 07774 9xxxxx |
| 0378 | Vodafone | 0378 xxxxxx | 07778 xxxxxx |
| 0385 0 | Vodafone | 0385 0xxxxx | 07785 0xxxxx |
| 0385 1 | Vodafone | 0385 1xxxxx | 07785 1xxxxx |
| 0385 2 | Vodafone | 0385 2xxxxx | 07785 2xxxxx |
| 0385 3 | Vodafone | 0385 3xxxxx | 07785 3xxxxx |
| 0385 5 | Vodafone | 0385 5xxxxx | 07785 5xxxxx |
| 0385 7 | Vodafone | 0385 7xxxxx | 07785 7xxxxx |
| 0385 8 | Vodafone | 0385 8xxxxx | 07785 8xxxxx |
| 0385 9 | Vodafone | 0385 9xxxxx | 07785 9xxxxx |
| 0390 | Orange | 0390 xxxxxx | 07790 xxxxxx |
| 0401 | BT Cellnet | 0401 xxxxxx | 07701 xxxxxx |
| 0402 | BT Cellnet | 0402 xxxxxx | 07702 xxxxxx |
| 0403 | BT Cellnet | 0403 xxxxxx | 07703 xxxxxx |
| 0408 | BT Cellnet Personal Assistant | 0408 xxxxxx | Discontinued by 28 April 2001 |
| 0410 | BT Cellnet | 0410 xxxxxx | 07710 xxxxxx |
| 0411 | BT Cellnet | 0411 xxxxxx | 07711 xxxxxx |
| 0421 | Vodafone | 0421 xxxxxx | 07721 xxxxxx |
| 0441 | Vodafone | 0441 xxxxxx | 07741 xxxxxx |
| 04481 | Guernsey Telecom | 04481 xxxxxx | 07781 xxxxxx |
| 0456 0 | Orange | 0456 0xxxxx | Unknown |
| 0456 1 | Orange | 0456 1xxxxx | Unknown |
| 04624 | Isle of Man | 04624 xxxxxx | 07624 xxxxxx |
| 0467 | Vodafone | 0467 xxxxxx | 07767 xxxxxx |
| 0468 | Vodafone | 0468 xxxxxx | 07768 xxxxxx |
| 0498 | Vodafone | 0498 xxxxxx | 07798 xxxxxx |
| 0585 | BT Cellnet | 0585 xxxxxx | 07885 xxxxxx |
| 0589 | BT Cellnet Vodafone? | 0589 xxxxxx | 07889 xxxxxx |
| 0802 | BT Cellnet | 0802 xxxxxx | 07802 xxxxxx |
| 0831 | Vodafone | 0831 xxxxxx | 07831 xxxxxx |
| 0836 | Vodafone | 0836 xxxxxx | 07836 xxxxxx |
| 0839 | Vodafone | 0839 xxxxxx | 07839 xxxxxx |
| 0850 | BT Cellnet | 0850 xxxxxx | 07850 xxxxxx |
| 0860 | BT Cellnet | 0860 xxxxxx | 07860 xxxxxx |
| 0930 7 | One-to-One | 0930 7xxxxx | 07930 7xxxxx |
| 0956 1 | One-to-One | 0956 1xxxxx | 07956 1xxxxx |
| 0956 2 | One-to-One | 0956 2xxxxx | 07956 2xxxxx |
| 0956 3 | One-to-One | 0956 3xxxxx | 07956 3xxxxx |
| 0956 4 | One-to-One | 0956 4xxxxx | 07956 4xxxxx |
| 0956 5 | One-to-One | 0956 5xxxxx | 07956 5xxxxx |
| 0956 6 | One-to-One | 0956 6xxxxx | 07956 6xxxxx |
| 0956 8 | One-to-One | 0956 8xxxxx | 07956 8xxxxx |
| 0956 9 | One-to-One | 0956 9xxxxx | 07956 9xxxxx |
| 0958 0 | One-to-One Freephone | 0958 0xxxxx | Discontinued by 28 April 2001 |
| 0958 1 | One-to-One Local Rate | 0958 1xxxxx | Discontinued by 28 April 2001 |
| 0958 2 | One-to-One | 0958 2xxxxx | 07958 2xxxxx |
| 0958 3 | One-to-One | 0958 3xxxxx | 07958 3xxxxx |
| 0958 4 | One-to-One | 0958 4xxxxx | 07958 4xxxxx |
| 0958 5 | One-to-One | 0958 5xxxxx | 07958 5xxxxx |
| 0958 6 | One-to-One | 0958 6xxxxx | 07958 6xxxxx |
| 0958 7 | One-to-One | 0958 7xxxxx | 07958 7xxxxx |
| 0958 8 | One-to-One | 0958 8xxxxx | 07958 8xxxxx |
| 0958 9 | One-to-One | 0958 9xxxxx | 07958 9xxxxx |
| 0961 0 | One-to-One | 0961 0xxxxx | 07961 0xxxxx |
| 0961 1 | One-to-One | 0961 1xxxxx | 07961 1xxxxx |
| 0961 2 | One-to-One | 0961 2xxxxx | 07961 2xxxxx |
| 0961 3 | One-to-One | 0961 3xxxxx | 07961 3xxxxx |
| 0961 4 | One-to-One | 0961 4xxxxx | 07961 4xxxxx |
| 0961 5 | One-to-One | 0961 5xxxxx | 07961 5xxxxx |
| 0961 6 | One-to-One | 0961 6xxxxx | 07961 6xxxxx |
| 0961 8 | One-to-One | 0961 8xxxxx | 07961 8xxxxx |
| 0961 9 | One-to-One | 0961 9xxxxx | 07961 9xxxxx |
| 0966 | Orange | 0966 xxxxxx | 07966 xxxxxx |
| 0973 | Orange | 0973 xxxxxx | 07973 xxxxxx |
| 0976 | Orange | 0976 xxxxxx | 07976 xxxxxx |
| 0979 7 | Jersey Telecom | 0979 7xxxxx | 07797 7xxxxx |
Pager numbers
The following codes for pager numbers were also changed, so that all are in the 076 range:| Code | Operator | Before BNC | After BNC |
| 0399 0 → 01399 0 | VodaPage | 0399 0xxxxx → 01399 0xxxxx | Discontinued by 28 April 2001 |
| 0399 1 → 01399 1 | VodaPage | 0399 1xxxxx → 01399 1xxxxx | 076 991x xxxx |
| 0399 2 → 01399 2 | VodaPage | 0399 2xxxxx → 01399 2xxxxx | 076 992x xxxx |
| 0399 3 → 01399 3 | VodaPage | 0399 3xxxxx → 01399 3xxxxx | 076 993x xxxx |
| 0399 4 → 01399 4 | VodaPage | 0399 4xxxxx → 01399 4xxxxx | 076 994x xxxx |
| 0399 5 → 01399 5 | VodaPage | 0399 5xxxxx → 01399 5xxxxx | 076 995x xxxx |
| 0399 6 → 01399 6 | VodaPage | 0399 6xxxxx → 01399 6xxxxx | 076 996x xxxx |
| 0399 7 → 01399 7 | VodaPage | 0399 7xxxxx → 01399 7xxxxx | 076 997x xxxx |
| 0399 8 → 01399 8 | VodaPage | 0399 8xxxxx → 01399 8xxxxx | 076 998x xxxx |
| 0399 9 → 01399 9 | VodaPage | 0399 9xxxxx → 01399 9xxxxx | 076 999x xxxx |
| 0426 → 01426 | BT Paging | 0426 xxxxxx → 01426 xxxxxx | 076 26xx xxxx |
| 0459 2→ 01459 2 | PageOne/Mercury | 0459 2xxxxx → 01459 2xxxxx | 076 592x xxxx |
| 0459 3→ 01459 3 | VodaPage | 0459 3xxxxx → 01459 3xxxxx | 076 593x xxxx |
| 0459 4→ 01459 4 | VodaPage | 0459 4xxxxx → 01459 4xxxxx | 076 594x xxxx |
| 0459 5→ 01459 5 | VodaPage | 0459 5xxxxx → 01459 5xxxxx | 076 595x xxxx |
| 0459 6→ 01459 6 | VodaPage | 0459 6xxxxx → 01459 6xxxxx | 076 596x xxxx |
| 0459 8→ 01459 8 | VodaPage | 0459 8xxxxx → 01459 8xxxxx | 076 598x xxxx |
| 0459 9→ 01459 9 | PageOne/Mercury | 0459 9xxxxx → 01459 9xxxxx | 076 599x xxxx |
| 01523 | PageOne | 01523 xxxxxx | 076 23xx xxxx |
| 01893 | BT Paging | 01893 xxxxxx | 076 93xx xxxx |
| 0336 7 | Vodafone | 0336 7xxxxx | 076 637x xxxx |
| 0385 4 | Vodata? | 0385 4xxxxx | Unknown |
| 0385 6 | Vodata | 0385 6xxxxx | Unknown |
| 04325 | BT Paging | 04325 xxxxxx | 076 25xx xxxx |
| 04624 | Isle of Man? | 04624 xxxxxx | 076 24xx xxxx |
| 0660 | PageOne | 0660 xxxxxx | 076 61xx xxxx |
| 0839 | PageOne | 0839 xxxxxx | 076 61xx xxxx |
| 0881 0 | PageOne | 0881 0xxxxx | 076 810x xxxx |
| 0881 4 | PageOne | 0881 4xxxxx | 076 814x xxxx |
| 0881 8 | PageOne | 0881 8xxxxx | 076 818x xxxx |
| 0941 | Orange | 0941 xxxxxx | 076 41xx xxxx |
| 0941 1 | Orange | 0941 1xxxxx | 076 411x xxxx |
Non-standard pager prefixes beginning 01 were moved to their new 076 allocation.
Some of these codes, as indicated by the arrow "→", had already been changed during PhONEday to add a "1" after the initial zero, and now they have been changed again.