United Kingdom Phone Number Guide

Quick Reference

• Country: United Kingdom of Great Britain and Northern Ireland
• Country Code: +44
• International Prefix: 00
• National Prefix: 0

---

Overview

This comprehensive guide explores the United Kingdom's telephone numbering plan, offering insights into number structures, dialing procedures, and regulatory frameworks. Essential for telecom professionals and developers, this guide ensures accurate handling of UK phone numbers.

Number Formats

General Number Structure

The UK's numbering plan, regulated by Ofcom, adheres to the ITU-T E.164 standard. Numbers vary by service type, such as geographic, mobile, or special services.

• Country Code: +44
• Trunk Code (National Prefix): 0
• Area Code: Varies (e.g., 020 for London, 0161 for Manchester)
• Subscriber Number: Varies by area code

Geographic Numbers

Geographic numbers are location-specific, typically starting with 01 or 02.

• Format: 0XXX XXX XXXX (for most areas)
• Example: 020 7946 0958 (London)

Mobile Numbers

UK mobile numbers start with 07 and are 11 digits long.

• Format: 07XXX XXXXXX
• Example: 07911 123456

Non-Geographic Numbers

Non-geographic numbers are used for services not tied to a location.

• 03 Numbers: Standard geographic rates

  • Format: 03XX XXX XXXX
  • Example: 0333 123 4567

• 08 Numbers: Freephone (0800, 0808) and special-rate services (084, 087)

  • Format: 08XX XXX XXXX
  • Example: 0800 123 4567 (Freephone)

• 09 Numbers: Premium-rate services

  • Format: 09XX XXX XXXX
  • Example: 0906 123 4567

Toll-Free Numbers

Toll-free numbers typically start with 0800 or 0808.

• Format: 0800 XXX XXX or 0808 XXX XXX
• Example: 0800 111 1111

Premium Rate Numbers

Premium services use the 09 prefix.

• Format: 09XX XXX XXXX
• Example: 0906 123 4567

Number Format Table

Type	Prefix	Example	Length
Geographic	01, 02	020 7946 0958	10 digits
Mobile	07	07911 123456	11 digits
Non-Geographic	03	0333 123 4567	10 digits
Freephone	0800, 0808	0800 111 1111	10 digits
Special Rate	084, 087	0845 123 4567	10 digits
Premium Rate	09	0906 123 4567	10 digits

Regular Expressions for Number Validation

To validate UK phone numbers, use these regular expressions:

• Geographic Numbers: ^0[1-2]\d{9}$
• Mobile Numbers: ^07\d{9}$
• Non-Geographic Numbers: ^0(?:3|8|9)\d{8}$
• Toll-Free Numbers: ^0800\d{6}$
• Premium Rate Numbers: ^09\d{8}$

Dialing Procedures

Domestic Calls

• Landline to Landline: Dial area code + subscriber number. Example: 020 7946 0958.
• Landline to Mobile: Dial mobile number directly. Example: 07911 123456.
• Mobile to Mobile: Dial mobile number directly. Example: 07911 123456.

International Calls

• Outgoing: Dial 00 + country code + national number. Example: 00 1 202 555 0123 (USA).
• Incoming: From abroad, dial +44 + UK number without leading 0. Example: +44 20 7946 0958.

Number Portability

The UK supports number portability, allowing retention of phone numbers when switching providers. Introduced for fixed-line in 2001 and mobile in 2003.

Major Telecom Operators

Major UK telecom operators include:

• EE (Everything Everywhere)
• O2
• Vodafone
• Three

These operators manage a wide range of mobile and fixed-line services. Mobile numbers typically start with 07.

Regulatory Authority

The UK's numbering plan is regulated by Ofcom. For updates, visit the Ofcom website.

ITU-T Recommendations

The UK follows the ITU-T E.164 standard, ensuring unique, globally formatted numbers.

Number Allocation and Management

Managed by Ofcom, numbers are allocated to operators who assign them to subscribers. Ofcom oversees special numbers like emergency and premium-rate services.

Technical Considerations

For Developers and Systems Administrators

• Validation: Use regular expressions for UK number validation.
• Normalization: Store numbers in international format (+44) to avoid ambiguity.
• Portability: Implement systems supporting number portability, especially for mobile numbers.
• Time Zones: Consider time zone differences for scheduling calls/messages to UK numbers.

---