E.123 international is a standard for formatting phone numbers, web addresses, and email addresses established by the International Telecommunication Union (ITU). Phone numbers that use this format (e.g., +1 123 456 789) are designed to ensure consistency and clarity in international communications.
How does the E.123 international phone number format work?
The E.123 international phone number format consists of:
- Plus sign (+): The standard prefix that indicates the subsequent number sequence is an international telephone number.
- Country code: A numerical code representing a specific country or region.
- Numbering Plan Area (NPA) code: The 1- to 3- digit area code identifying the specific geographic region within a country. Note that this is also called a “dialing code” in some regions.
- Local number: The unique number assigned to a specific person within a numbering plan area.
E.123 international vs. E.123 national
While E.123 international includes a plus sign (+) followed by the country code and phone number, E.123 national uses parentheses to separate the area code and local number.
Unlike the plus sign in international numbers, the parentheses in E.123 national are not mandatory and can be omitted when dialing from within the same country.
E.123 national is regulated by the same standard as E.123 international, which provides the formatting guidelines for telephone numbers, email addresses, and web addresses published by the ITU.
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