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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:


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.

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Last update:
‎11-24-2023 06:24 AM
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