E.164

Shahzad_Ismail — Fri, 24 Nov 2023 14:24:03 GMT

An ITU-T (International Telecommunication Union - Telecommunication Standardization Sector) standard that defines global telephone number format. As described by the ITU, the E.164 general format must contain only digits split as follows:

A leader plus sign (`+`)
Country code (max 3 digits)
Subscriber number (max 12 digits)

For example, a US phone number would be rendered like this:
[+][1][1234567890]

The following examples demonstrate the format:

US phone number: +11234567890

UK phone number: +4407123456789

SE phone number: +461234567890

We often refer to a telephone number as a MSISDN – Mobile Station International Subscriber Directory Number – for example, a telephone number using international E.164 format. This term is used in quite a few messaging documents. It is sometimes pronounced as “miz-din.” The term: MDN – or Mobile Directory Number – also refers to a telephone number, using the international E.164 format.

article E.164 in Glossary

E.164