Sign In

12th April 2023

How many numbers in a phone number

How+many+numbers+in+a+phone+number Image

Telephone numbers have a long and complex history. As the world of phones has evolved and changed, new challenges have arisen that have continued to alter the way phone numbers are assigned and used. 

In fact, the entire system in the UK has been overhauled several times, and there have frequently been regions that avoided efforts to homogenise the structure. Because of this, there’s actually no standardised number of digits in a UK telephone number. 

History of UK phone numbers 

Household telephones were first available in the early 20th century in the UK. In the early days of telephones, no numbers were dialled at all - the operator would manually connect the caller to the recipient. 

In 1912, the first ‘automatic’ phone exchange was introduced in the UK. This meant a call within the area could be connected without the need for an operator. 

In 1958, Subscriber Trunk Dialling (STD) codes were introduced. These codes were dialled before the subscriber number and allowed people to make calls outside of their local area without needing to go through an operator. These regional codes would eventually evolve into the area codes we know today. 

How many digits in a phone number? 

UK land line phone number range from three to eleven digits. The most common number of digits in a UK phone number are ten or eleven. 

Three-digit phone numbers

Some phone numbers are only three digits long - the most famous examples are 999, 112 and 111. 

Four- to five-digit phone numbers

Four- and five-digit codes are used to test phone lines, call back numbers or reveal concealed numbers, such as 1471. 

Six- to seven-digit phone numbers

A few six- or seven-digit numbers are used to access various support services, such as the Samaritans (116 123). There are no eight-digit numbers in use in the UK. 

Standard UK phone number length

A standard UK landline will normally have ten or eleven digits. If the phone number displays with the UK’s international dialling code ( 44) this might result in a longer phone number.


What do the digits in a phone number mean? 

A phone number will be made of several different parts. For a standard landline, this will always include:

An area code 

A subscriber number

The area code will be shared between all the landlines in a certain area. The subscriber number identifies the specific landline within that area. 

Area codes can be anywhere between two and five digits long. Subscriber numbers can then be five to eight digits long.  

If you are receiving a call from outside the UK, an international dialling code might be displayed along with the phone number following a “ ” sign. 

Sometimes if you are getting a call on your mobile, an international code might be displayed even if the call is coming from within the UK. In this case, you will see “ 44” followed by the caller’s area code and subscriber number. 

How many digits in a mobile phone number? 

Mobile numbers in the UK have eleven digits (twelve if the county code is included). Mobile numbers will also always start with “07” or “ 447”, depending on whether the country code is displayed or not. 

Some mobile number prefixes can tell you how long a number has been in use and which carrier it was originally provided by. 

Further information:


Simunix is the development team behind We also offer our services via T2A Web Services API, 118 365 directory assistance number and our powerful corporate service; ORBIS.

Find out more

News Enquiries

Andrew Talbot

Head of Communications

[email protected]

Social Media

Latest Tweets


Your web browser is out of date

Some features on will be disabled or give unexpected results.
Please update your browser to get the best experience on this website.

Your web browser is too old

This website requires a newer browser to function correctly, please update your browser to continue.