E.164

Last updated
Recommendation ITU-T E.164
The international public telecommunication numbering plan
StatusIn force
Year started1984
Latest versionJune 2020
Organization ITU-T
CommitteeStudy Group 2
Related standards E.123, E.163
Domain telephony
Website https://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.

Contents

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 E.163 was withdrawn, and some recommendations were incorporated into revision 1 of E.164 in 1997.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 +991 for the purpose of conducting an international non-commercial trial. [4]

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 telecommunication.

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 international call prefixes, necessary for a call to reach international circuits from inside the country of call origination.

Geographic areas

Country CodeNational Destination CodeSubscriber Number
1 to 3 digitsmaximum 15 digits − number of digits in the Country Code
maximum 15 digits

Global services

Country CodeGlobal Subscriber Number
3 digitsmaximum 12 digits
maximum 15 digits

[1] Figure 2

Networks

Country CodeIdentification CodeSubscriber Number
3 digits1 to 4 digitsmaximum 12 digits − number of digits in the Identification Code
maximum 15 digits

Groups of countries

Country CodeGroup Identification CodeSubscriber Number
3 digits1 digitmaximum 11 digits
maximum 15 digits

Trials

Fixed codeTrial Identification CodeSubscriber Number
9911 digitmaximum 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 (+) indicates that the number should be dialed with an international calling prefix, in place of the plus sign. The number is presented starting the country calling code. This is called the globalized format of an E.164 number, and is defined in the Internet Engineering Task Force RFC 2806. [6] The international calling prefix is a trunk code to reach an international circuit in the country of call origination. [7]

DNS Mapping of E.164 numbers

Some national telephone administrations and telephone companies have implemented an Internet-based database for their numbering spaces. E.164 numbers may be registered in the Domain Name System (DNS) of the Internet in which the second-level domain e164.arpa has been reserved for telephone number mapping (ENUM). In the system, any telephone number may be mapped into a domain name using a reverse sequence of subdomains for each digit. For example, the telephone number +19995550123 translates to the domain name 3.2.1.0.5.5.5.9.9.9.1.e164.arpa. When a number is mapped, a DNS query may be used to locate the service facilities on the Internet that accept and process telephone calls to the owner of record of the number, using, for example, the Session Initiation Protocol (SIP), a call-signaling VoIP protocol whose SIP addresses are similar in format (user@domain...) to e-mail addresses. This allows a direct, end-to-end Internet connection without passing through the public switched telephone network.

See also

External Sources

Related Research Articles

A country code is a short alphanumeric identification code for countries and dependent areas. Its primary use is in data processing and communications. Several identification systems have been developed.

<span class="mw-page-title-main">North American Numbering Plan</span> Integrated telephone numbering plan of twenty North American countries

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A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks.

E.123 is an international standard by the standardization union (ITU-T), entitled Notation for national and international telephone numbers, e-mail addresses and web addresses. It provides guidelines for the presentation of telephone numbers, email addresses, and web addresses in print, on letterheads, and similar purposes.

MSISDN is a number uniquely identifying a subscription in a Global System for Mobile communications or a Universal Mobile Telecommunications System mobile network. It is the mapping of the telephone number to the subscriber identity module in a mobile or cellular phone. This abbreviation has several interpretations, the most common one being "Mobile Station International Subscriber Directory Number".

International direct dialing (IDD) or international subscriber dialling (ISD) is placing an international telephone call, dialed directly by a telephone subscriber, rather than by a telephone operator. Subscriber dialing of international calls typically requires an international call prefix to be dialed before the country code.

<span class="mw-page-title-main">Telephone numbers in Europe</span>

Telephone numbers in Europe are managed by the national telecommunications authorities of each country. Most country codes start with 3 and 4, but some countries that by the Copenhagen criteria are considered part of Europe have country codes starting on numbers most common outside of Europe.

<span class="mw-page-title-main">Telephone numbers in Italy</span>

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<span class="mw-page-title-main">Telephone numbers in Sweden</span>

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<span class="mw-page-title-main">Telephone numbers in Taiwan</span>

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<span class="mw-page-title-main">Telephone numbers in Thailand</span>

Thailand's telephone numbering plan in Thailand is managed by the National Broadcasting and Telecommunications Commission (NBTC) in accordance with International Telecommunication Union's (ITU) recommendation E.164.

Telephone numbers in Canada follow the fixed-length format of the North American Numbering Plan (NANP) of a three-digit area code, a three-digit central office code, and a four-digit station or line code. This is represented as NPA NXX XXXX.

<span class="mw-page-title-main">Telephone numbers in Russia</span>

Telephone numbers in Russia are administered by Roskomnadzor, and Ministry of Digital Development, Communications and Mass Communications of the Russian Federation. Russia's National Numbering Plan (NNP) is a four-level telephone numbering plan with local, zone, country, and international scopes, implementing a closed numbering plan, in which the number of digits of all national significant numbers (NSN) assigned to subscriber telephones is fixed at ten, with three digits for the area code, and a seven-digit subscriber number which includes a zone code of up to two digits. Internationally, Russia participates in the numbering plans of the International Telecommunication Union (ITU) provided by recommendations E.164 and E.123, using the telephone country code 7.

<span class="mw-page-title-main">Telephone number</span> Sequence of digits assigned to a telephone subscription

A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN) or other public and private networks.

<span class="mw-page-title-main">Telephone numbers in Kazakhstan</span>

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Telephone numbers in San Marino have six to ten digits. Numbers starting with either 0, 8 or 9 are assigned to landlines, 6 is used for mobile services, 5 for IP telephony services and 7 for premium numbers. No trunk prefixes are used: all the digits are always dialed.

<span class="mw-page-title-main">Telephone numbers in Panama</span>

All telephone numbers in Panama are seven or eight digits long and there are no area codes. All numbers that both begin with 6 and have 8 digits are mobile numbers. All landline numbers have 7 digits. The first digit of landline numbers may be used to vaguely identify the location of the caller. Mobile phones were also assigned 7 digit numbers until 2005, when they were moved to their own number space with 8 digits. Mobile numbers are recycled if the user is marked as inactive by the mobile service provider, and landline numbers are also recycled if a user cancels their landline phone service.

The Belize telephone numbering plan is the system used for assigning telephone numbers in Belize.

References

  1. 1 2 "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.
  2. ↑ "E.163 : Numbering plan for the international telephone service". www.itu.int. Archived from the original on 2019-07-29. Retrieved 2019-11-12.
  3. ↑ "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.
  4. ↑ "E.164.2 : E.164 numbering resources for trials". www.itu.int. Archived from the original on 2019-11-12. Retrieved 2019-11-12.
  5. ↑ "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.
  6. ↑ URLs for Telephone Calls. IETF. April 2000. sec. 2.2. doi: 10.17487/RFC2806 . RFC 2806 . Retrieved January 11, 2021.
  7. ↑ Olsen, Chris (2011-08-01). Implementing Cisco Unified Communications Manager, Part 2 (CIPT2) Foundation Learning Guide: (CCNP Voice CIPT2 642-457). Cisco Press. p. 172. ISBN   9780132312141.
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