United Kingdom (+44 / 0044): 9 to 10 digits
Locals write 07400 123456. An API wants +447400123456. Paste any United Kingdom number below to see it normalised, validated, and identified.
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How United Kingdom numbers are written
- Country calling code
- +44
- Dialled from abroad
- 0044 (011 44 from the US and Canada)
- ISO country code
- GB
- National number length
- 9 to 10 digits
- Trunk prefix
- 0 (dropped in E.164)
- Written locally
- 07400 123456
- E.164 format
- +447400123456
What +44 means
+44 is the country calling code for United Kingdom. The same code is written 0044 when you dial out from most of Europe, Africa and Asia, and 011 44 from the US and Canada. All three reach the same place: only the exit code in front of it changes. Whichever one you use, the national trunk 0 is dropped once the country code is in front.
Mobile numbers
Mobiles start with 7 (written 07 nationally).
Converting to E.164
Take the number as written locally (07400 123456), drop the leading 0, then prefix +44. The result is +447400123456: no spaces, no dashes, no parentheses. Store that, and format for display only when you show it to a human.
Why not do it with a regex
A pattern that matches United Kingdom numbers today breaks the moment a new mobile range is allocated, and it cannot tell you whether the number is actually assigned. The tool above runs the same numbering-plan engine as our phone validation API, so it also reports line type and region rather than just shape.
United Kingdom mobile prefixes
- 071xx – 075xx
- Mobile
- 07624
- Isle of Man mobile
- 077xx – 079xx
- Mobile
A prefix tells you the range a number was issued from, not which network holds it today — numbers move between operators. For the current carrier you need a live lookup, which is what our phone API returns.
United Kingdom area codes by city
- London
- 020
- Birmingham
- 0121
- Manchester
- 0161
- Edinburgh
- 0131
- Glasgow
- 0141
- Leeds
- 0113
London numbers are 020, not 0207 or 0208
The area code is 020 and the subscriber number is eight digits beginning 7, 8 or 3. Writing 0207 123 4567 splits the number in the wrong place — it is 020 7123 4567. The habit dates from 1990s codes that no longer exist, and it still breaks dialling from abroad, where the correct form is +44 20 7123 4567.
UK numbers reserved for drama
Ofcom sets aside these ranges so that television, radio and film do not send an audience to a real person's phone. They are equally the right choice for a screenshot, a test fixture or a form placeholder: nothing in them can ever ring.
| Range | Where it belongs |
|---|---|
| 07700 900000 to 900999 | Mobile |
| 020 7946 0000 to 0999 | London |
| 0113 496 0000 to 0999 | Leeds |
| 0114 496 0000 to 0999 | Sheffield |
| 0115 496 0000 to 0999 | Nottingham |
| 0116 496 0000 to 0999 | Leicester |
| 0117 496 0000 to 0999 | Bristol |
| 0118 496 0000 to 0999 | Reading |
| 0121 496 0000 to 0999 | Birmingham |
| 0131 496 0000 to 0999 | Edinburgh |
| 0141 496 0000 to 0999 | Glasgow |
| 0151 496 0000 to 0999 | Liverpool |
| 0161 496 0000 to 0999 | Manchester |
| 0191 498 0000 to 0999 | Tyneside, Durham and Sunderland |
| 028 9649 6000 to 6999 | Northern Ireland |
| 029 2018 0000 to 0999 | Cardiff |
| 01632 960000 to 960999 | No real area — reserved nationally |
| 08081 570000 to 570999 | Freephone |
| 0909 8790000 to 8790999 | Premium rate |
| 03069 990000 to 990999 | UK-wide |
Source: Ofcom — Telephone numbers for use in TV and radio drama programmes, read 2026-08-07.
United Kingdom phone numbers, answered
How do I write a UK phone number in international format?
Drop the leading 0 and add +44. 07700 900123 becomes +447700900123; 020 7123 4567 becomes +442071234567. The 0 is a national trunk prefix and never appears after +44.
How many digits is a UK mobile number?
Ten after the +44, eleven as written at home. UK mobiles all start 07 nationally, which is 7 after the country code.
Which UK numbers are safe to use as examples?
Ofcom reserves 07700 900000–900999 for drama and documentation, along with equivalent landline ranges. They are never allocated to real subscribers, so they are the correct numbers to put in test data and screenshots.
That is how a United Kingdom number is written. Whether a whole list is worth dialling is the free call list cleaner, or check one number on the spam phone checker.