E.164 is an ITU-T recommendation, titled The international public telecommunication numbering plan, that defines a numbering plan for the world-wide Public Switched Telephone Network (PSTN) and some other data networks.

E.164 defines a general format for International Telephone Numbers. Plan-conforming Phone Numbers are limited to a maximum of 15 digits, excluding the International Direct Dialling (IDD).

The presentation of a Phone Number is usually prefixed with the plus sign (+), indicating that the Phone Number includes the Number Plan Area. When dialing, the Phone Number must typically be prefixed with the appropriate international call prefix (in place of the plus sign), which is a Trunk Code to reach an international circuit from within the country of call origination.

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

E.164 International Telephone Number formats#

E.164 Numbering formats are limited to a total of 15 Digits and defined into the following categories:

E.164 is a number is designed to include all of the necessary information to successfully route a call to an individual subscriber on a nation's public telephone network. Here's how the E.164 numbering plan works:

National Destination Code and Subscriber Number together are collectively called the National Significant Number

E.164 allows each country to decide how many digits should be in the National Destination Code and the Subscriber Number.

The possibilities are nearly endless. A 15-digit number allows for 100 trillion different Numbers. (enough for each person on earth to have 10,000 phone numbers)

E.164 numbers can be mapped to a Uniform Resource Identifier (URI) the use of the Domain Name System (DNS) and the Dynamic Delegation Discovery System (DDDS) as described in RFC 6116

Example E.164 Number#

An Example E.164 Number you might use as +1 (804)-222-1111 x1234. This number would be defined as: Parsing Result (parseAndKeepRawInput())
  • Country Calling Code: 1
  • National Significant Number: 8042221111
  • extension: 1234
  • country_code_source FROM_NUMBER_WITH_PLUS_SIGN
  • italian_leading_zero false
  • raw_input: +1 (804)-222-1111 x1234
  • Phone Number region: US
  • E.164 format: +18042221111
  • Original format: +1 804-222-1111 x1234
  • National format: (804) 222-1111
  • International format: +1 804-222-1111
  • Out-of-country format from US: 1 (804) 222-1111
  • Out-of-country format from CH: 00 1 804-222-1111
  • Phone Number Off-line Geolocation: Richmond, VA
  • Time zone(s): America/New_York
  • Carrier:

E.164 Regular expression#

Ldapwiki has used this Regular expression for testing strings as proper formatted of E.164 Phone Numbers:

More Information#

There might be more information for this subject on one of the following:
  • [#1] - E.164 - based on data observed:2015-05-18