What is the country code for GB?

The country code for the United Kingdom of Great Britain and Northern Ireland is +44.

How are mobile numbers structured in GB?

Mobile numbers in the UK start with the prefix 07 and are 11 digits long, formatted as 07XXX XXXXXX. For example, a valid mobile number could be 07911 123456.

What are the dialing procedures for international calls to GB?

To call a UK number from abroad, dial the international access code (e.g., 00), followed by the UK country code (+44), and then the UK number without the leading 0. For example, to call the London number 020 7946 0958 from abroad, you would dial +44 20 7946 0958.

Is number portability supported in GB?

Yes, the UK supports number portability for both mobile and fixed-line numbers. This allows users to retain their phone numbers when switching between service providers.

What are the major telecom operators in GB and their typical number ranges?

The major telecom operators in the UK include EE, O2, Vodafone, and Three. Mobile numbers typically start with the prefix 07, which is common across all these operators.

What is the national prefix for UK numbers?

The national prefix for UK numbers is 0.

What is the country code for the United Kingdom?

The country code for the United Kingdom is +44.

How do I dial a UK number from abroad?

To dial a UK number from abroad, use the format: +44 followed by the UK number without the leading 0. For example, +44 20 7946 0958.

What are some examples of UK geographic area codes?

Examples of UK geographic area codes include 020 for London and 0161 for Manchester.

How do I dial a UK landline number domestically?

To dial a UK landline number domestically, dial the area code followed by the subscriber number, such as 020 7946 0958.

What is the standard length of a UK mobile number?

A UK mobile number is typically 11 digits long.

What prefixes do UK mobile numbers start with?

UK mobile numbers start with the prefix 07.

What are non-geographic numbers in the UK?

Non-geographic numbers in the UK are used for services not tied to a specific location and include prefixes like 03, 08, and 09.

What is the format for UK toll-free numbers?

UK toll-free numbers typically start with 0800 or 0808 and are formatted as 0800 XXX XXX.

How are UK premium-rate numbers formatted?

UK premium-rate numbers use the 09 prefix and are formatted as 09XX XXX XXXX.

What is number portability in the UK?

Number portability in the UK allows users to retain their phone numbers when switching providers, available for fixed-line since 2001 and mobile since 2003.

Who regulates the UK telephone numbering plan?

The UK telephone numbering plan is regulated by Ofcom.

What is the international dialing prefix for calling out of the UK?

The international dialing prefix for calling out of the UK is 00.

What are the major telecom operators in the UK?

Major telecom operators in the UK include EE, O2, Vodafone, and Three.

How can developers validate UK phone numbers?

Developers can validate UK phone numbers using regular expressions specific to each number type, such as geographic, mobile, and non-geographic numbers.

What is the ITU-T E.164 standard?

The ITU-T E.164 standard is an international numbering plan that ensures unique, globally formatted numbers.

What prefix do UK freephone numbers use?

UK freephone numbers use the prefixes 0800 and 0808.

How are UK special-rate numbers formatted?

UK special-rate numbers, such as those beginning with 084 and 087, are formatted as 08XX XXX XXXX.

What should be considered when scheduling calls to UK numbers?

When scheduling calls to UK numbers, consider time zone differences to ensure appropriate timing.

What is the purpose of non-geographic numbers in the UK?

Non-geographic numbers in the UK are used for services that are not location-specific, such as customer service lines and helplines.

United Kingdom Phone Numbers: Format, Area Code & Validation Guide

This guide provides a detailed overview of United Kingdom phone number formats, covering everything from basic structure and area codes to regular expressions for validation. Understanding these formats is crucial for businesses operating in the UK, developers working with telephony applications, and anyone seeking to effectively communicate with UK contacts.

UK Phone Numbering System Overview

The UK's phone numbering system is a complex but well-organized structure managed by Ofcom (Office of Communications). It has evolved over time, adapting to technological advancements and growing demand. The system categorizes numbers into several key types:

Geographic Numbers: Tied to specific geographic locations within the UK. These numbers begin with 01 or 02.
Mobile Numbers: Used for mobile phones and other wireless communication devices. These numbers begin with 07.
Non-Geographic Numbers: Not linked to a specific location. These include numbers starting with 03 (charged at standard geographic rates), 08 (special-rate services), and 09 (premium-rate services).

Geographic Numbers

Geographic numbers reflect the UK's regional structure. They are further divided based on area codes, which vary in length depending on the population density and historical development of the telephone network in that region.

Area Code Structure

Area codes can be 2, 3, 4, or even 5 digits long (after the initial 0). Shorter area codes are typically assigned to densely populated areas like major cities, allowing for a larger number of individual phone numbers within that region.

2-Digit Area Codes (Format: 02X): Used for major metropolitan areas. The most prominent example is 020 for London.
3-Digit Area Codes (Format: 01X1 or 011X): Cover large areas and cities. Examples include 0117 for Bristol (011X) and 0121 for Birmingham (01X1).
4-Digit Area Codes (Format: 01XXX): Typically assigned to smaller towns and rural areas. An example is 01946 for Whitehaven.
5-Digit Area Codes (Format: 01XXXX): These are less common and exist in a few specific areas, often due to historical reasons or the need to accommodate a large number of lines within a smaller geographic area. Examples include 01335 for Ashbourne and 01773 for Belper. These often have shorter local numbers (5 or 6 digits).

Geographic Number Format

The standard format for a geographic number is 0XXX XXX XXXX (where XXX represents the area code). The total length, including the area code, is usually 10 digits. However, in some rare cases with 5-digit area codes, the total length can be 9 digits.

Example: 020 7946 0958 (London number)

Mobile Numbers

Mobile numbers in the UK always start with 07 and are 10 digits long. They are further categorized into specific ranges:

070: Personal Numbering Services. These include virtual mobile numbers, follow-me services, and personal assistant services. It's important to note that these numbers are often charged at a higher rate than standard mobile numbers.
071-075 & 077-079: Used for standard mobile phone services, mobile broadband, and machine-to-machine (M2M) communications. While both ranges serve similar purposes, the 077-079 range represents newer allocations and also includes some legacy paging services and allocations for IoT (Internet of Things) device connectivity.

Non-Geographic Numbers

Non-geographic numbers offer businesses and organizations a national presence without being tied to a specific location.

03 Numbers

03 numbers are charged at the same rate as standard geographic calls and are often included in mobile phone inclusive minutes. They are widely used by:

Corporate contact centers
Government services
Healthcare providers
Educational institutions

08 Numbers

08 numbers are special-rate services and their costs can vary significantly. Businesses using 08 numbers are legally required to clearly disclose call charges. These numbers are categorized into:

0800/0808 (Freephone): Free to call from landlines and mobiles.
0843/0844 (Business Rate): Charged at a higher rate than geographic numbers.
0871/0872/0873 (Higher Rate): Charged at a premium rate. These are often used for premium support services, entertainment services, and information lines.

09 Numbers

09 numbers are premium-rate services and are typically used for services like adult entertainment, competitions, and voting lines. These numbers carry the highest call charges.

Validating UK Phone Numbers with Regular Expressions

Regular expressions provide a powerful way to validate UK phone numbers. Here are some robust patterns based on Ofcom's guidelines:

// Geographic Numbers (including variations in length)
const geoPattern = /^(?:(?:\+44\s?|0)(?:(?:[1-5]\d{8,9}|[1-5]\d{3}[-\s]?\d{3}[-\s]?\d{3,4})))$/;

// Mobile Numbers
const mobilePattern = /^(?:(?:\+44\s?|0)7(?:[1-5|7-9])\d{8})$/;

// Freephone and Special Rate (0800, 0808, 084x, 087x)
const specialPattern = /^(?:(?:\+44\s?|0)8(?:0(?:0|8)|4[3-4]|7[0-3])\d{7})$/;

// Premium Rate (09)
const premiumPattern = /^(?:(?:\+44\s?|0)9\d{8})$/;

// All UK Numbers (Combined)
const allUkPattern = /^(?:(?:\+44\s?|0)(?:(?:[1-5]\d{8,9}|[1-5]\d{3}[-\s]?\d{3}[-\s]?\d{3,4})|7(?:[1-5|7-9])\d{8}|8(?:0(?:0|8)|4[3-4]|7[0-3])\d{7}|9\d{8}))$/;

Explanation of Regex Components

^ and $: Match the beginning and end of the string, ensuring the entire string is a valid number.
(?: ... ): Non-capturing group.
\+44\s?|0: Matches either the international prefix "+44" with an optional space or the national trunk prefix "0".
\d{n}: Matches exactly n digits.
[1-5|7-9]: Matches a single digit within the specified range.
[-\s]?: Matches an optional hyphen or whitespace character, allowing for different formatting styles.

Best Practices for Phone Number Validation

Sanitize Input: Before validation, remove any non-digit characters except the "+" sign.
Informative Error Messages: Provide specific error messages to guide users towards correct input.
Consider User Experience: Allow for various formatting styles (e.g., spaces, hyphens) in user input.
Regularly Update Regex: Keep your regex patterns up-to-date with Ofcom's numbering plan changes.

By following these guidelines and using the provided regular expressions, you can effectively validate UK phone numbers and ensure accurate communication. This comprehensive understanding of UK phone number formats is essential for any developer or business interacting with UK customers.