E.164

Recommendation ITU-T E.164
The international public telecommunication numbering plan
StatusIn force
Year started1984
Latest versionJune 2020
OrganizationITU-T
CommitteeStudy Group 2
Related standardsE.123, E.163
Domaintelephony
Websitehttps://www.itu.int/rec/T-REC-E.164/

E.164 is an international standard (ITU-T Recommendation), titled The international public telecommunication numbering plan, that defines a numbering plan for the worldwide public switched telephone network (PSTN) and some other data networks.

E.164 defines a general format for international telephone numbers. Plan-conforming telephone numbers are limited to only digits and to a maximum of fifteen digits.[1] The specification divides the digit string into a country code of one to three digits, and the subscriber telephone number of a maximum of twelve digits.

Alternative formats (with area codes and country specific numbers) are available. Any country-specific international call prefixes are not contained in the specification.

The title of the original version and first revision of the E.164 standard was Numbering Plan for the ISDN Era

  1. ^ "E.164 : The international public telecommunication numbering plan". www.itu.int. p. 11. Archived from the original on 2019-11-06. Retrieved 2019-11-12.