🇬🇧Reading UK numbers

How to read a UK phone number

A UK number has an area code, a local number and, for international calls, the +44 country code. From abroad you replace the leading zero with +44, so 020 7946 0123 becomes +44 20 7946 0123.

What you get

  • Area code plus local number, usually ten digits
  • From abroad, drop the leading zero and add +44
  • Dial the international form from your browser
How it works
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🇬🇧

How it works

1

Open StartACall

Open it in your browser and create an account in under a minute.

2

Type +44 and the number

Use +44, drop the leading zero, then add the rest of the number.

3

Press call

The call connects in a few seconds, in HD voice. Your first call is free.

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How to read a UK phone number

In short

A UK number has three parts: the area code, the local number and, for international calls, the country code +44. Written nationally it starts with a zero, like 020 7946 0123. From abroad you replace that leading zero with +44, so the same number becomes +44 20 7946 0123.

The three parts of a UK number

Every UK number breaks down into an area code and a local number. A London example written nationally looks like 020 7946 0123, where 020 is the area code and 7946 0123 is the local number. The whole thing is usually ten digits after the leading zero, eleven digits including it, which is a useful check when you are not sure you have copied a number correctly.

Mobiles follow the same idea. A mobile written as 07123 456789 has 07123 as the mobile prefix and the rest as the subscriber number. There is no city behind a mobile prefix, it simply marks the line as a mobile, so you cannot tell where the person is from the number alone.

The leading zero and the +44 country code

The leading zero you see in 020 or 07123 is a trunk prefix used only inside the UK. When you call from another country you remove that zero and put the UK country code +44 in front instead. This swap is the single most important thing to get right.

So 020 7946 0123 becomes +44 20 7946 0123 from abroad, and the mobile 07123 456789 becomes +44 7123 456789. Forgetting to drop the zero is the most common reason an international call to the UK fails to connect, because the network sees an extra digit it does not expect.

Spotting landlines, mobiles and special numbers

Reading the prefix also tells you what kind of line you are calling. A number starting 01 or 02 is a geographic landline, one starting 07 is a mobile, and one starting 08 is a special number such as freephone 0800. This matters because mobiles cost more to reach than landlines.

If a UK number starts with 03 it is non geographic but charged like a normal landline. Recognising these patterns at a glance means you know roughly what a call will cost before you place it, even without looking the rate up.

Reading it the easy way with the browser

With StartACall you only ever need the international form. Type the plus sign, the country code 44 and the rest of the number without its leading zero, then press call from your browser. The dialler handles the rest, so you never have to think about access codes.

There is no app to install and no SIM to swap. The call goes from your browser tab straight to the UK landline or mobile, so once you can read the number correctly you can place the call in seconds. The first call is free with no card, billing is per minute and the credit you add never expires. A UK landline costs about $0.0514 per minute and a UK mobile about $0.0955 per minute, with a small $0.004 connection fee per call, so reading the number is really the only thing you need to get right before you press call.

Frequently asked questions

What is the country code for the UK?+

The UK country code is +44. You put it in front of the number, after removing the leading zero, when calling from outside the UK.

Why does a UK number start with a zero?+

The leading zero is a trunk prefix used only for dialling within the UK. It is dropped when you call from abroad and replaced with +44.

How do I write a London number for international callers?+

Take 020 7946 0123 and turn it into +44 20 7946 0123. The 020 loses its zero and gains the +44 country code in front.

How long is a UK phone number?+

Most UK numbers are ten digits after the leading zero, or eleven digits including it. London and mobile numbers both follow this pattern.

Do mobiles use an area code?+

No. A mobile prefix like 07123 is not tied to any place. It only marks the line as a mobile, unlike geographic 01 and 02 codes.

Last reviewed June 2026Reviewed by the StartACall calling teamDialing rules cross checked against ITU international dialing procedures
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