UK Phone Number Format

UK numbers are 10–11 digits including a leading 0. Landlines start 01 or 02 followed by an area code; mobiles start 07; freephone uses 0800 or 0808. In international format, drop the leading 0 and add +44. London’s 020 7946 0958 becomes +44 20 7946 0958 when dialled from abroad.

This guide breaks down the full UK number format — landline, mobile, freephone, premium, and special-rate ranges — with spacing conventions, international vs domestic formatting, and a side-by-side comparison with the US number format. For the wider country-code background, see the UK phone codes guide hub.

UK phone number anatomy

Every UK phone number has three parts when written in national format:

1. The trunk prefix 0 — a single digit that signals “this is a long-distance number inside the UK”.
2. The number range prefix — 1, 2, 3, 5, 7, 8, or 9 — which identifies what kind of number it is (geographic landline, mobile, freephone, etc.).
3. The subscriber digits — the unique part of the number, usually 8 or 9 digits.

Prefix	Number type	Total digits	Example
01	Geographic landline (non-metro)	10–11	0113 496 0123 (Leeds)
02	Geographic landline (large city)	11	020 7946 0958 (London)
03	UK-wide non-geographic	11	0300 123 1234 (NHS)
05	Corporate / VoIP	11	0500 number range (retired)
07	Mobile	11	07700 900123
08	Freephone / special-rate	11	0800 / 0808 / 0843 / 0844
09	Premium-rate	11	0906 / 0909

The total length, including the leading 0, is almost always 11 digits. The handful of 10-digit numbers are legacy assignments in a few smaller geographic areas (e.g. some 01 ranges in Tyneside or Brighton).

Landline number format

UK landlines are split into two ranges: 01 for the rest of the country and 02 for the largest metropolitan zones. The split is historical — Ofcom moved the biggest cities into 02 in the 2000s to free up 01 numbering space.

Geographic 01 landlines (non-metro)

01 area codes are 4 or 5 digits including the leading 0. Most regional towns and rural areas live here.

• 0113 xxx xxxx — Leeds (4-digit area code)
• 0114 xxx xxxx — Sheffield
• 0117 xxx xxxx — Bristol
• 0118 xxx xxxx — Reading
• 01225 xxx xxx — Bath (5-digit area code)
• 01506 xxx xxx — Livingston

When the area code is 4 digits, the local subscriber number is 7 digits. When the area code is 5 digits, the local number is 6 digits. Total always equals 11 digits.

Geographic 02 landlines (large city)

02 area codes are exactly 3 digits including the leading 0. Only the biggest UK conurbations got them.

• 020 xxxx xxxx — London
• 023 xxxx xxxx — Southampton / Portsmouth
• 024 xxxx xxxx — Coventry
• 028 xxxx xxxx — Northern Ireland (whole country)
• 029 xxxx xxxx — Cardiff

The London area code is 020, not 0207 or 0208. A London number is correctly written 020 7946 0958. Writing 0207 946 0958 is a common mistake that misrepresents the area code.

Mobile number format

UK mobile numbers all start with 07 and are 11 digits long. The format is fixed:

07xxx xxx xxx

The four digits after the 0 (the 07xxx block) identify the original allocation to an operator — though number portability now lets subscribers move between networks while keeping the same number, so the prefix no longer guarantees the current carrier.

07 range	Original allocation	Notes
074xx	EE / O2 / Vodafone	Original major-operator block
075xx	EE	Migrated assignments
077xx	Vodafone / Three	High-volume range
078xx	O2 / EE	Includes corporate batches
079xx	Mixed UK MNOs	Spans all big networks
070xx	Personal numbers (NOT mobile)	Forwarding service — premium-rate-style charging

The 070 block deserves a warning: it looks like a mobile number but is a personal-numbering range that can charge callers high per-minute rates. Treat it as special-rate, not mobile.

For business buyers, see how operator portability works in our number porting explainer.

Freephone, premium, and special-rate numbers

The 08 and 09 ranges cover all the non-geographic, non-mobile UK numbers, and the cost to the caller differs sharply between prefixes:

Prefix	Type	Cost to caller	Common use
0800, 0808	Freephone	Free from landlines AND mobiles (since 2015)	Customer service, government helplines
0300	UK-wide standard	Same as 01/02 — included in inclusive minutes	NHS, councils, charities
0345, 0344	UK-wide standard	Same as 01/02 — included in inclusive minutes	Banks, large retailers
0843, 0844, 0845	Business-rate	7p/min service charge + access charge	Customer service (declining)
0871, 0872, 0873	Business-rate (high)	13p/min service charge + access charge	Reservations, tickets
09xx	Premium-rate	Up to £3.60/min + access charge	Competitions, voting, adult

Since 2015, 0800 and 0808 are genuinely free from UK mobiles, not just from landlines — a regulatory change that resolved a long-standing consumer complaint. The 03 range was introduced as a “geographic-rate non-geographic” option so charities and public bodies could publish a single UK-wide number that was still included in inclusive-minute bundles.

Spacing conventions for UK numbers

Ofcom publishes presentation rules for how to space written UK numbers. The point of spacing is to make the area code and the subscriber block visually distinct.

Number type	Correct presentation	Avoid
London landline	020 7946 0958	0207 946 0958, 02079460958
4-digit area code	0113 496 0123	01134 960 123
5-digit area code	01225 460 123	0122 546 0123
Mobile	07700 900123 or 07700 900 123	077 0090 0123
Freephone	0800 123 1234	08001231234

The international format follows the same logic with +44 replacing the leading 0 and a space between the country code and the area code:

+44 20 7946 0958     (London)
+44 113 496 0123     (Leeds)
+44 7700 900123      (mobile)
+44 800 123 1234     (freephone)

For business buyers presenting numbers on a website, in email signatures, or on call-routing trees — the schema-friendly presentation is always the international format with the +44 prefix.

International vs domestic format

There are exactly two ways to write any UK number, and the only difference is how the leading 0 is handled.

Domestic (national) format

• Used when dialling from another UK number.
• Keep the leading 0.
• Example: 020 7946 0958.

International (E.164) format

• Used when dialling from outside the UK, when configuring international call-routing, or when filing the number into any schema.org / CRM field.
• Drop the leading 0 and prefix +44.
• Example: +44 20 7946 0958.

The mistake to avoid: keeping the 0 and adding +44. The combination +44 020 7946 0958 is not a valid UK number — most networks will route it, but some VoIP systems and international carriers will reject it.

If you are calling the UK from the US, dial the US international access code first (011), then the UK country code, then drop the leading 0. Full step-by-step in how to call UK from US.

UK vs US number format compared

The two formats look different but follow the same logical structure — a country code, an area code, and a subscriber number. The biggest practical differences are the trunk prefix (UK has one, US doesn’t), the length (US is fixed at 10, UK varies 10–11), and the freephone ranges.

Feature	UK	US
Country code	+44	+1
Trunk prefix when dialling domestically	0	None
Total digits (national format)	10–11 (incl. leading 0)	10 (no prefix)
Area code length	2–5 digits (after the 0)	3 digits
Mobile prefix	07	None — mobile and landline share area codes
Freephone	0800, 0808	800, 888, 877, 866, 855, 844, 833
Premium-rate	09	900, 976
Written example	020 7946 0958	(415) 555 0123
International form	+44 20 7946 0958	+1 415 555 0123

The single biggest gotcha for US-based teams calling UK numbers: drop the 0. A US system that tries to dial +44 0 20 7946 0958 will fail. The 0 belongs only in the domestic UK presentation.

If you’re a US business setting up a UK virtual number with DialPhone business phone, the system will store every UK number in E.164 format (+44… with no leading 0) and present it locally as 0xxx for UK-side callers.

Number portability between operators

UK number portability has been mandatory since 1999 (landline) and 2007 (mobile). Subscribers can keep their existing number when switching networks, so the original allocation prefix is no longer a reliable indicator of the current carrier.

• Mobile porting (07 numbers) — takes 1 working day under Ofcom’s General Conditions, using the Porting Authorisation Code (PAC) the current operator must issue within minutes of a request.
• Landline porting (01 / 02) — takes 5–10 working days. Geographic numbers can move between providers but cannot move between area codes — a Leeds 0113 number stays a Leeds number even if the customer moves to a Bristol-based VoIP provider.
• Non-geographic porting (03, 0800, 0808) — typically takes 10–15 working days.

Because UK numbers are portable, the network displayed in a “07xxx” lookup tool is the historic allocation, not necessarily the current carrier. Real-time HLR lookups (used by SMS providers and PSAP systems) return the current operator. For more on porting workflows, see our number porting glossary entry.

Related guides

• UK phone codes guide — full +44 country code hub
• How to call UK from US — step-by-step dialling
• Number porting — keeping your number between operators
• DialPhone business phone — UK virtual numbers in E.164 format

FAQ

Frequently asked questions

What does a UK phone number look like? +

A UK phone number has 10 or 11 digits including a leading 0. Landlines start with 01 or 02 followed by an area code and a local number, while mobiles start with 07 and total 11 digits. In international format the leading 0 is dropped and +44 is added, so the London landline 020 7946 0958 becomes +44 20 7946 0958.

How many digits is a UK mobile number? +

A UK mobile number is exactly 11 digits in national format, including the leading 0. The format is 07xxx xxx xxx — the 07 prefix identifies it as a mobile, followed by a four-digit operator block and a six-digit subscriber number. In international format the same number becomes +44 7xxx xxx xxx, which is 12 digits including the country code.

What is the format for a UK landline? +

UK landlines use a 10- or 11-digit format depending on the area code length. Geographic landlines start with 01 (most of the UK) or 02 (large cities like London 020, Cardiff 029, Belfast 028). The pattern is 0 + area code (2 to 5 digits) + local number, with total length usually 10 or 11 digits. London numbers are written 020 7xxx xxxx — the area code is 020, not 0207.

Why do UK numbers start with 0? +

The leading 0 is the UK national trunk prefix. It tells the network that the rest of the digits are a domestic area code, not a local extension. When you dial internationally you drop the 0 and replace it with +44, because the country code already signals a long-distance call. The trunk 0 only exists for callers dialling inside the UK.

Are UK area codes the same length everywhere? +

No. UK area codes range from 2 digits (London 020, the largest) up to 5 digits (small rural exchanges like 016977 Brampton). Most are 4 or 5 digits. The total number length stays at 10 or 11 digits — shorter area codes pair with longer local numbers, and vice versa. Mobile, freephone, and premium ranges all use fixed 4-digit prefixes after the 0.