E.164
The international public telecommunication numbering plan | |
Status | In force |
---|---|
Year started | 1984 |
Latest version | June 2020 |
Organization | E.163 |
Domain | telephony |
Website | https://www.itu.int/rec/T-REC-E.164/ |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/31/Phone_number_setup.png/220px-Phone_number_setup.png)
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
Recommendations
E.163
E.163 was the former ITU-T recommendation for describing telephone numbers for the public switched telephone network (PSTN). In the United States, this was formerly referred to as a directory number. E.163 was withdrawn, and some recommendations were incorporated into revision 1 of E.164 in 1997.[2]
E.164.1
This recommendation describes the procedures and criteria for the reservation, assignment, and reclamation of E.164 country codes and associated identification code (IC) assignments.[3] The criteria and procedures are provided as a basis for the effective and efficient utilization of the available E.164 numbering resources.
E.164.2
This recommendation contains the criteria and procedures for an applicant to be temporarily assigned a three-digit identification code within the shared E.164 country code
E.164.3
This recommendation describes the principles, criteria, and procedures for the assignment and reclamation of resources within a shared E.164 country code for groups of countries.[5] These shared country codes will coexist with all other E.164-based country codes assigned by the ITU. The resource of the shared country code consists of a country code and a group identification code (CC + GIC) and provides the capability for a group of countries to provide telecommunication services within the group. The Secretariat of the ITU Standardization Sector (ITU-T), the Telecommunication Standardization Bureau (TSB) is responsible for the assignment of the CC + GIC.
Numbering formats
The E.164 recommendation provides the telephone number structure and functionality for five categories of telephone numbers used in international public
For each of the categories, it details the components of the numbering structure and the digit analysis required for successful routing of calls. Annex A provides additional information on the structure and function of E.164 numbers. Annex B provides information on network identification, service parameters, calling/connected line identity, dialing procedures, and addressing for Geographic-based ISDN calls. Specific E.164-based applications which differ in usage are defined in separate recommendations.
The number categories are all based on a fifteen-digit numbering space. Before 1997, only twelve digits were allowed. The definition does not include any
Geographic areas
Country Code | National Destination Code | Subscriber Number |
---|---|---|
1 to 3 digits | maximum 15 digits − number of digits in the country code | |
maximum 15 digits |
Global services
Country Code | Global Subscriber Number |
---|---|
3 digits | maximum 12 digits |
maximum 15 digits |
[1] Figure 2
Networks
Country Code | Identification Code | Subscriber Number |
---|---|---|
3 digits | 1 to 4 digits | maximum 12 digits − number of digits in the identification code |
maximum 15 digits |
Groups of countries
Country Code | Group Identification Code | Subscriber Number |
---|---|---|
3 digits | 1 digit | maximum 11 digits |
maximum 15 digits |
Trials
Fixed code | Trial Identification Code | Subscriber Number |
---|---|---|
991 | 1 digit | maximum 11 digits |
maximum 15 digits |
Uses of E.164 numbers
E.164 numbers were originally defined for use in the worldwide public switched telephone network (PSTN). The early PSTN collected routing digits from users (e.g. on a dial pad), signaled those digits to each telephony switch, and used the numbers to determine how to ultimately reach the called party.
ITU-T E.123 entitled Notation for national and international telephone numbers, e-mail addresses and web addresses provides guidance when printing E.164 telephone numbers. This format includes the recommendation of prefixing international telephone numbers with a plus sign (+) and using only spaces for digit grouping.
The presentation of a telephone number with the plus sign (
DNS Mapping of E.164 numbers
Some national telephone administrations and telephone companies have implemented an
See also
- Carrier of Record
- E.123
- List of country calling codes
External Sources
References
- ^ a b "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.
- ^ "E.163 : Numbering plan for the international telephone service". www.itu.int. Archived from the original on 2019-07-29. Retrieved 2019-11-12.
- ^ "E.164.1 : Criteria and procedures for the reservation, assignment and reclamation of E.164 country codes and associated identification codes (ICs)". www.itu.int. Archived from the original on 2019-11-12. Retrieved 2019-11-12.
- ^ "E.164.2 : E.164 numbering resources for trials". www.itu.int. Archived from the original on 2019-11-12. Retrieved 2019-11-12.
- ^ "E.164.3 : Principles, criteria and procedures for the assignment and reclamation of E.164 country codes and associated identification codes for groups of countries". www.itu.int. Archived from the original on 2019-11-12. Retrieved 2019-11-12.
- . Retrieved January 11, 2021.
- ISBN 9780132312141.