The E.164 Numbering Standard
Posted: Mon May 19, 2025 7:10 am
3.1 Overview
The E.164 recommendation by the ITU defines the international public telecommunication numbering plan. It standardizes phone numbers globally to ensure uniformity and interoperability across networks and countries.
An E.164 number:
Has a maximum of 15 digits
Includes the country code and iceland phone number data subscriber number
Excludes local prefixes (like the trunk prefix "0")
Example:
A US phone number: +1 650 253 0000
A UK phone number: +44 20 7946 0958
3.2 Benefits of E.164
Global interoperability: Ensures calls and messages can be routed accurately.
Unique identifiers: No duplication of phone numbers across countries.
Support for mobile and VoIP: Facilitates modern communication technologies.
Compatibility with mobile numbering plans and services.
4. Local vs. International Formats
Understanding the difference between local and international formats is crucial for making successful calls.
4.1 Local Format
This is how you dial a number within the same country. It may include the trunk prefix and area code.
Example (UK):
Local: 020 7946 0958
4.2 International Format
This includes the country code and omits the trunk prefix. It is the format used for dialing from outside the country.
Example (UK):
International: +44 20 7946 0958
5. Mobile Phone Number Structure
Mobile numbers differ from landlines in that:
They often have specific prefixes (e.g., 07 in the UK)
Area codes may represent carriers rather than regions
Portability allows numbers to be transferred between networks
5.1 Example: Mobile Number (India)
Local: 09876543210
International: +91 9876543210
Here:
"91" is the country code
"98" identifies the mobile carrier
The rest is the unique subscriber number
6. Special Number Formats
6.1 Toll-Free Numbers
Toll-free numbers are free for the caller. They typically begin with special prefixes like:
800, 888, 877 (USA/Canada)
0800 (UK)
1800 (India)
These numbers route to businesses and are often used for customer service.
The E.164 recommendation by the ITU defines the international public telecommunication numbering plan. It standardizes phone numbers globally to ensure uniformity and interoperability across networks and countries.
An E.164 number:
Has a maximum of 15 digits
Includes the country code and iceland phone number data subscriber number
Excludes local prefixes (like the trunk prefix "0")
Example:
A US phone number: +1 650 253 0000
A UK phone number: +44 20 7946 0958
3.2 Benefits of E.164
Global interoperability: Ensures calls and messages can be routed accurately.
Unique identifiers: No duplication of phone numbers across countries.
Support for mobile and VoIP: Facilitates modern communication technologies.
Compatibility with mobile numbering plans and services.
4. Local vs. International Formats
Understanding the difference between local and international formats is crucial for making successful calls.
4.1 Local Format
This is how you dial a number within the same country. It may include the trunk prefix and area code.
Example (UK):
Local: 020 7946 0958
4.2 International Format
This includes the country code and omits the trunk prefix. It is the format used for dialing from outside the country.
Example (UK):
International: +44 20 7946 0958
5. Mobile Phone Number Structure
Mobile numbers differ from landlines in that:
They often have specific prefixes (e.g., 07 in the UK)
Area codes may represent carriers rather than regions
Portability allows numbers to be transferred between networks
5.1 Example: Mobile Number (India)
Local: 09876543210
International: +91 9876543210
Here:
"91" is the country code
"98" identifies the mobile carrier
The rest is the unique subscriber number
6. Special Number Formats
6.1 Toll-Free Numbers
Toll-free numbers are free for the caller. They typically begin with special prefixes like:
800, 888, 877 (USA/Canada)
0800 (UK)
1800 (India)
These numbers route to businesses and are often used for customer service.