Itu-t rec. e.164 (05/97) the international public telecommunication numbering plan
SERIES E: OVERALL NETWORK OPERATION,TELEPHONE SERVICE, SERVICE OPERATION ANDHUMAN FACTORS
Operation, numbering, routing and mobile services –International operation – Numbering plan of theinternational telephone service
4HE INTERNATIONAL PUBLIC TELECOMMUNICATION
OVERALL NETWORK OPERATION, TELEPHONE SERVICE, SERVICE OPERATION AND HUMAN OPERATION, NUMBERING, ROUTING AND MOBILE SERVICES
General provisions concerning Administrations
Operation of international telephone services
Numbering plan of the international telephone service E.160–E.169
Maritime mobile service and public land mobile service
OPERATIONAL PROVISIONS RELATING TO CHARGING AND ACCOUNTING IN
Charging in the international telephone service
Procedures for remuneration of Administrations for facilities made available
Measuring and recording call durations for accounting purposes
Establishment and exchange of international accounts
UTILIZATION OF THE INTERNATIONAL TELEPHONE NETWORK FOR NON-
QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING
QUALITY OF TELECOMMUNICATION SERVICES: CONCEPTS, MODELS,
For further details, please refer to ITU-T List of Recommendations.ITU-T RECOMMENDATION E.164 THE INTERNATIONAL PUBLIC TELECOMMUNICATION NUMBERING PLAN
This Recommendation provides the number structure and functionality for the three categories of numbers used forinternational public telecommunication – they are geographic areas, global services and Networks. For each of thecategories, it details the components of the numbering structure and the digit analysis required to successfully route thecalls. Annex A provides additional information on the structure and function of E.164 numbers. Annex B providesinformation on network identification, service parameters, calling/connected line identity, dialling procedures andaddressing for geographic-based ISDN calls. Specific E.164-based applications which differ in usage are defined inseparate Recommendations.
ITU-T Recommendation E.164 was revised by ITU-T Study Group 2 (1997-2000) and was approved under the WTSCResolution No. 1 procedure on the 26th of May 1997. Recommendation E.164 (05/97) FOREWORD
ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommuni-cations. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T isresponsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view tostandardizing telecommunications on a worldwide basis.
The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes thetopics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics.
The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSCResolution No. 1.
In some areas of information technology which fall within ITU-T’s purview, the necessary standards are prepared on acollaborative basis with ISO and IEC.
In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunicationadministration and a recognized operating agency.
The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve theuse of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicabilityof claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendationdevelopment process.
As of the date of approval of this Recommendation, the ITU had/had not received notice of intellectual property,protected by patents, which may be required to implement this Recommendation. However, implementors are cautionedthat this may not represent the latest information and are therefore strongly urged to consult the TSB patent database.
All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation E.164 (05/97) CONTENTS
International public telecommunication number structure.
International public telecommunication number length .
Structure of the international public telecommunication number.
Assignment of Identification Codes .
International public telecommunication number for geographic areas .
International public telecommunication number for global services .
Evolution path to an international public telecommunication number for global services.
International public telecommunication number for Networks.
Annex A – Clarification and explanation of the structure and function of E.164 numbers .
Unique identification of international number for geographic areas .
Unique identification of international number for global services .
Unique identification of international number for Networks .
Annex B – Application of international public telecommunication numbers for ISDN . Recommendation E.164 (05/97) Recommendation E.164 Recommendation E.164 (05/97) THE INTERNATIONAL PUBLIC TELECOMMUNICATION NUMBERING PLAN Introduction
The rapid advances in telecommunication technology coupled with increased diversification of customer demandsserved by a number of different types of dedicated public switched networks (telephone, telex, data, etc.) have created aneed to provide a uniform customer access to the multitude of network structures (i.e. ISDN, IN, etc.). Implementationof these network architectures has begun in a number of countries and eventually these will be able to carry the fullrange of existing and new services.
To provide a broad base for these new arrangements, numbering has been kept compatible with that originallyestablished for international telephone service. As covered in this Recommendation, numbering for ISDN and theinternational telephone service are an integral part of this international telecommunication numbering plan.
This Recommendation provides the number structure and functionality for the three categories of numbers used forinternational public telecommunication – they are geographic areas, global services, and Networks. For each of thecategories, it details the components of the numbering structure and the digit analysis required to successfully route thecalls. Annex A provides additional information on the structure and function of E.164 numbers. Annex B providesinformation on network identification, service parameters, calling/connected line identity, dialling procedures andaddressing for geographic-based ISDN calls. Specific E.164-based applications which differ in usage are defined inseparate Recommendations, e.g. Recommendation E.168 – Application of E.164 numbering plan for UPT. References
The following ITU-T Recommendations and other references contain provisions which, through reference in this text,constitute provisions of this Recommendation. At the time of the publication, the editions indicated were valid. AllRecommendations and other references are subject to revision. All users of this Recommendation are thereforeencouraged to investigate the possibility of applying the most recent edition of the Recommendation and otherreferences listed below. A list of the current valid ITU-T Recommendations is regularly published.
CCITT Recommendation E.123 (1988), Notation for national and international telephone numbers.
CCITT Recommendation E.131 (1988), Subscriber control procedures for supplementary telephone services.
ITU-T Recommendation E.164.11, Criteria and procedures for the assignment of E.164 country codes andassociated identification codes.
CCITT Recommendation E.165 (1988), Timetable for coordinated implementation of the full capability of thenumbering plan for the ISDN era (Recommendation E.164).
ITU-T Recommendation E.165.1 (1996), Use of escape code "0" within the E.164 numbering plan during thetransition period to implementation of NPI mechanism. Recommendation E.164 (05/97)
ITU-T Recommendation E.166/X.122 (1996), Numbering plan interworking for the E.164 and X.121numbering plans.
ITU-T Recommendation E.168 (1993), Application of E.164 numbering plan for UPT.
ITU-T Recommendation E.169 (1996), Application of Recommendation E.164 numbering plan for universalinternational freephone numbers for international freephone service.
ITU-T Recommendation E.190 (1997), Principles and responsibilities for the management, assignment andreclamation of E-Series international numbering resources.
ITU-T Recommendation E.191 (1996), B-ISDN numbering and addressing.
CCITT Recommendation E.213 (1988), Telephone and ISDN numbering plan for land mobile stations inPublic Land Mobile Networks (PLMN).
CCITT Recommendation E.214 (1988), Structure for the land mobile global title for the SignallingConnection Control Part (SCCP).
CCITT Recommendation E.331 (1991), Minimum user-terminal interface for a human user entering addressinformation into an ISDN terminal.
CCITT Recommendation I.330 (1988), ISDN numbering and addressing principles. Definitions
Within the integrated service environment, the terms used for all networks and services must be compatible andconsistent. This Recommendation defines the following terms. F: numéroS: número
A string of decimal digits that uniquely indicates the public network termination point. The number contains theinformation necessary to route the call to this termination point.
A number can be in a format determined nationally or in an international format. The international format is known asthe International Public Telecommunication Number which includes the country code and subsequent digits, but not theinternational prefix. numbering plan F: plan de numérotageS: plan de numeración
A numbering plan specifies the format and structure of the numbers used within that plan. It typically consists of decimaldigits segmented into groups in order to identify specific elements used for identification, routing and charging capa-bilities, e.g. within E.164 to identify countries, national destinations, and subscribers.
A numbering plan does not include prefixes, suffixes, and additional information required to complete a call.
The national2 numbering plan is the national implementation of the E.164 numbering plan.
For the purposes of this Recommendation, national is defined as a country, group of countries, global service or Network. Recommendation E.164 (05/97) dialling plan F: plan de numérotationS: plan de marcación
A string or combination of decimal digits, symbols, and additional information that defines the method by which thenumbering plan is used. A dialling plan includes the use of prefixes, suffixes, and additional information, supplementalto the numbering plan, required to complete the call. F: adresseS: dirección
A string or combination of decimal digits, symbols, and additional information which identifies the specific terminationpoint(s) of a connection in a public network(s) or, where applicable, in interconnected private network(s). F: préfixeS: prefijo
A prefix is an indicator consisting of one or more digits, that allows the selection of different types of number formats,networks and/or service. international prefix F: préfixe internationalS: prefijo internacional
A digit or combination of digits used to indicate that the number following is an International Public TelecommunicationNumber. country code (CC) for geographic areas F: indicatif de pays pour zones géographiquesS: indicativo de país para áreas geográficas
The combination of one, two or three digits identifying a specific country, countries in an integrated numbering plan, ora specific geographic area. national (significant) number [N(S)N] F: numéro national (significatif) [N(S)N]S: número nacional (significativo) [N(S)N]
That portion of the number that follows the country code for geographic areas. The national (significant) numberconsists of the National Destination Code (NDC) followed by the Subscriber Number (SN). The function and format ofthe N(S)N is nationally determined. national destination code (NDC) F: indicatif national de destination (NDC)S: indicativo nacional de destino (NDC)
A nationally optional code field, within the E.164 number plan, which combined with the Subscriber’s Number (SN) willconstitute the national (significant) number of the international public telecommunication number for geographic areas. The NDC will have a network and/or trunk code selection function.
The NDC can be a decimal digit or a combination of decimal digits (not including any prefix) identifying a numberingarea within a country (or group of countries included in one integrated numbering plan or a specific geographic area)and/or network/services. Recommendation E.164 (05/97) national (trunk) prefix F: préfixe (interurbain) nationalS: prefijo (interurbano) nacional
A digit or combination of digits used by a calling subscriber, making a call to a subscriber in his own country but outsidehis own numbering area. It provides access to the automatic outgoing trunk equipment. trunk code (TC) F: indicatif interurbain (TC)S: indicativo interurbano (TC)
A digit or combination of digits, not including the national (trunk) prefix, identifying the numbering area within acountry (or group of countries included in one integrated numbering plan or a specific geographic area).
The trunk code has to be used before the called subscriber’s number when the calling and called subscribers are indifferent numbering areas. The trunk code is a particular application of NDC. destination network (DN) code F: indicatif de réseau de destination (DN)S: indicativo de red de destino (DN)
An optional code field within the E.164 numbering plan which identifies the destination network serving the destinationsubscriber. It performs the destination network selection function of the NDC. In some instances it can be combined witha trunk code to form the NDC. The DN code can be a decimal digit or a combination of decimal digits (not including anyprefix). country code (CC) for global services F: indicatif de pays pour les services mondiauxS: indicativo de país para servicios mundiales
A 3-digit Country Code used to identify the global service. global service F: service mondialS: servicio mundial
A service defined by the ITU-T, provisioned on the public switched network, to which the ITU-T has assigned a specificcountry code to enable the provision of that international service between two or more countries and/or integratednumbering plans. global subscriber number (GSN) F: numéro d'abonné mondial (GSN)S: número de abonado mundial (GSN)
The number identifying a subscriber for a particular global service. country code (CC) for Networks F: indicatif de pays pour les RéseauxS: indicativo de país para Redes
A shared 3-digit Country Code used in combination with an identification code to identify an international Network.
Internationally interconnected physical nodes and operational systems operated and maintained by one or more ROAs toprovide public telecommunications services. Private networks are not included in this definition. Note that the use ofcapital "N" in Networks indicates that this definition applies. Recommendation E.164 (05/97) identification code (IC) F: code d’identification (IC)S: código de identificación (SC)
The code subsequent to a shared E.164 country code that uniquely identifies an international Network. subscriber number (SN) F: numéro d'abonné (SN)S: número de abonado (SN)
The number identifying a subscriber in a network or numbering area. escape code F: code d'échappementS: código de escape
One or more digits which indicate that the digits that follow are from a specific numbering plan which is different fromthe originating numbering plan.
An escape code can be carried forward through the originating network and can be carried across internetwork andinternational boundaries. Therefore the digits used for escape codes should be standardized. Abbreviations
This Recommendation uses the following abbreviations.
International Telegraph and Telephone Consultative Committee
International Telecommunication Union – Telecommunication Standardization Sector
Recommendation E.164 (05/97) International public telecommunication number structure
This clause identifies three different structures for the international public telecommunication number:
International public telecommunication number for geographic areas.
International public telecommunication number for global services.
International public telecommunication number for Networks. International public telecommunication number length
The ITU-T recommends that the maximum number of digits for the international geographic, global services, andnetwork applications should be 15 (excluding the international prefix). Administrations are invited to do their utmost tolimit the digits to be dialled to the degree possible consistent with the service needs. Structure of the international public telecommunication number
The international public telecommunication number for geographic areas (Figure 1) is composed of a variable
number of decimal digits arranged in specific code fields. The international public telecommunication number codefields are the Country Code (CC) and the National (Significant) Number N(S)N .
Figure 1 shows the international public telecommunication number structure for geographic areas.
NDC National Destination Code (optional)SN Subscriber
NOTE – National and international prefixes are not part of the international public telecommunication number forgeographic areas. Figure 1/E.164 – International public telecommunication number structure for geographic areas
The international public telecommunication number for global services (Figure 2) is composed of decimal
digits that vary depending on the specific service. The international service number code fields are the 3-digit countrycode and the Global Subscriber Number (GSN).
Figure 2 shows the international public telecommunication number structure for global services. The use of this format isservice specific and is dependent on the numbering requirements as detailed in the appropriate Recommendation,e.g. Recommendation E.169 – Application of Recommendation E.164 numbering plan for universal internationalfreephone numbers for international freephone service. Recommendation E.164 (05/97)
NOTE – National and international prefixes are not considered to be part of the international public telecommuni-cation number for global services. Figure 2/E.164 – International public telecommunication number structure for global services
The international public telecommunication number for Networks (Figure 3) is composed of decimal digits
arranged in three code fields. The code fields are the 3-digit shared Country Code (CC) field, the IC field, which variesin length between 1 to 4 digits, and the Subscriber Number (SN) which can be up to 15 minus the number of digits in theCC and IC fields.
Figure 3 shows the international public telecommunication number for Networks.
Number of digits in Identification Code (IC)
NOTE – National and international prefixes are not part of the international public telecommunication number forNetworks. Figure 3/E.164 – International public telecommunication number structure for Networks Assignment of Country Codes (CCs)
Country codes may be assigned to either geographic areas, global services or shared among Networks. Recommendation E.164 (05/97)
The status of country codes for geographic areas, global services, and Networks is published periodically by
All spare country codes will be assigned on a three-digit basis.
The assignment and reservation of country codes shall follow the criteria and procedures as defined in
Assignment of Identification Codes
The list of assigned and reserved identification codes with their associated country codes is published
The assignment and reservation of identification codes shall follow the criteria and procedures as defined in
International public telecommunication number for geographic areas
Principles, criteria and procedures for the assignment of international public telecommunication numbers for geographicareas may be found in Recommendations E.190 and E.164.1. Country Code for geographic areas
The Country Code is used to select the destination country3 and varies in length from 1 to 3 digits. National (significant) number
The ITU-T recommends that the maximum number of digits of the National (Significant) Number, N(S)N,
should be equal to 15-n, where n is the number of digits of the country code.
The N(S)N is used to select the destination subscriber. In selecting the destination subscriber, however, it may
be necessary to select a destination network. To accomplish this selection, the N(S)N code field comprises a NationalDestination Code (NDC) followed by the Subscriber’s Number (SN). The NDC and SN may be inseparably connected insome national applications to form a single composite dialling sequence.
The NDC field, if used, will be variable in length depending upon the requirements of the destination country.
Each NDC may have one of the following structures:
a Destination Network (DN) code, which can be used to select a destination network serving the destinationsubscribers;
any combination of Destination Network (DN) code and Trunk Code (TC).
The NDCs of an Administration may consist of one of the above structures or others as defined by nationalAdministrations.
NOTE – The sequences DN-TC and TC-DN are a national matter. The various NDC options (TC/DN) are reflected in Figure 4.
The SN varies in length depending on the requirements of the destination country.
Where appropriate, identification of a specific network within the destination country shall be through the use
of a NDC incorporated in the public telecommunication number.
Whenever the term country, destination country or originating country is used in this subclause, it identifies a specific country, agroup of countries in an integrated numbering plan or a specific geographical area. Recommendation E.164 (05/97) Figure 4/E.164 – Options for NDC structure Prefixes Applications
A prefix is an indicator consisting of one or more digits that allows the selection of different types of number formats,networks and/or service. Prefixes are not part of the number and are not signalled over international boundaries. It is anational matter to decide whether prefixes can be signalled between domestic networks.
Prefixes can also be used for carrier network and service selection nationally. National (trunk) prefix
The national (trunk) prefix is not included in N(S)N. Accordingly, in the international service, the national (trunk) prefixof the country of destination must not be dialled.
It should be noted that, in some countries, it is customary to consider for national purposes that the national (trunk)prefix is included in the national number which is then not the N(S)N. A careful distinction must therefore be madebetween such national definition or practice and the ITU-T definition, which is internationally valid. In order to avoidmisunderstanding, the ITU-T definition includes the word "significant" between brackets, reading as follows: "national(significant) number".
It is recommended by the ITU-T that the Administrations of countries that have not yet adopted a trunk prefix for accessto their national automatic trunk network adopt a prefix composed of a single digit, preferably 0. Irrespective of whatdigit is adopted as a trunk prefix, this digit should be precluded from being used also as a first digit of the N(S)N.
to provide the maximum degree of standardization of the national (trunk) prefixes used in different countries, sothat dialling is made as easy as possible for a person travelling from one country to another;
to minimize the number of digits to be dialled;
to reduce user problems which arise because of the requirement, in automatic international operation, that the trunkprefix of the country of destination must not be dialled.
In the automatic international service, following the international prefix and country code of the called country, thecaller should dial the N(S)N of the called subscriber [i.e. without dialling the national (trunk) prefix].
The use and printing of symbols and separators in national and international telephone numbers are detailed inRecommendation E.123. Recommendation E.164 (05/97) National numbering plan Characteristics of national numbering plan
Each Administration should give the most careful consideration to the preparation of a national numbering plan for itsown network. This plan should be designed:
to allow generous provision for future growth in the number of subscribers and services to the national system;
with the consideration that the national network will ultimately be accessible to subscribers in other countries bymeans of international dialling procedures;
so that subscribers would always be called by either the same N(S)N or SN, a national matter, regardless of wherethe call originated from within the national numbering plan.
The numbering plan will be based on and evolve from the existing numbering plans applicable to national andinternational public telephone networks.
Where multiple destinations (i.e. ROAs/networks) serve the called party’s geographical area, the national numberingarrangement in the country of destination shall provide for discrimination between these ROAs/networks. The procedurefor discrimination between multiple transit ROAs/networks is not considered to be a destination address requirement andshall therefore be excluded from these numbering arrangements.
The ten-digit decimal character set 0-9 is used throughout the numbering plan format including subscriber number,national (significant) number and the country code.
Prefixes and other information concerned with identifying selection procedures or Network Service parameters (such asQuality of Service or transit delay) do not form part of the number.
An integrated numbering plan shall include an unambiguous identification of a particular country. In addition, thenumber will identify networks within these countries, if required. Notification of national numbering changes
Administrators should advise the ITU-T, on a non-binding informational basis, of significant national numbering planchanges well in advance of the event, so that this information can be published by the TSB. It is recommended that thisnotification be submitted at least 2 years in advance to ensure formal and timely information to the widest possibledistribution.
Resource administrators are encouraged to inform other resource administrators of significant national numbering planchanges well in advance of its implementation. Digit analysis
the originating country must analyze a number of digits of the E.164 international number. The length of the NationalDestination Code (NDC) increases the potential requirement for number analysis because it provides for a combinationof either a Trunk Code (TC) and/or a network identification function. Careful consideration should be given to thepreparation of the National Destination Code (NDC) assignments.
On international calls the number analysis performed at the originating country need not be more than the
four digits of the N(S)N in the case of a country with a three-digit country code;
five digits of the N(S)N in the case of a country with a two-digit country code;
six digits of the N(S)N in the case of a country with a one-digit country code. Recommendation E.164 (05/97)
Although the potential for seven-digit analysis exists, it is not required for every call. The terminating country willinform the originating country which of the seven dialled digits of the E.164 number will indicate when seven-digitanalysis is required. Some Administrations will be able to implement the charging arrangements with seven-digitanalysis at the same time as the associated routing. Others may not be able to implement the charging arrangements atthe same time; bilateral arrangements should be agreed with these Administrations.
The national numbering plan of a country should be such that digit analysis for incoming international calls
need not exceed established limits applicable to the N(S)N but allows:
determination of routing that reflects economic and other appropriate network factors;
distinctions for charging in those countries where distinctions are applicable. International public telecommunication number for global services
The numbering plan for global services is service specific. Each use of an E.164 country code for a global service needsto comply with numbering assignment principles, as specified in Recommendation E.190, as identified for the specificservice, and the criteria and procedures as specified in Recommendation E.164.1. Refer to the appropriate numberingRecommendation for documentation regarding the numbering scheme and any service specific principles,e.g. Recommendation E.168 – Application of E.164 numbering plan for UPT.
The international public telecommunication number for global services is composed of the 3-digit country code appliedfor the global service and the Global Subscriber Number (GSN). The maximum length is 15 digits (see Figure 2). Country Code for global services
The country code for a global service is used to identify the global service and is three digits in length. Global Subscriber Number
The Global Subscriber Number (GSN) consists of the digits following the country code for the global service. Thestructure and functionality of these digits is application dependent and will be addressed in the appropriate global servicenumbering Recommendations, e.g. Recommendation E.169 – Application of Recommendation E.164 numbering planfor universal international freephone numbers for international freephone service. Digit analysis
Digit analysis for global services is service specific. In order to determine the specific global service, and the call routingand charging, the digit analysis should not exceed 7 digits, e.g. 3-digit CC + 4 digits of N(S)N. Refer to the appropriateITU-T numbering Recommendation for documentation regarding the number analysis requirements for the specificglobal service. Evolution path to an international public telecommunication number for global services
The development of a numbering plan for a global service should consider the possibility for the subscribers, whoalready have a number for the same comparable domestic service, to evolve their domestic Subscriber Number (SN) tothe Global Subscriber Number (GSN).
It is assumed that ITU-T recognized global services will be location independent.
If in the implementation of the global service there are duplicate numbering requests and there are no service specificresolution procedures, then the duplicate request procedures should be invoked as defined in Recommendation E.169 –Application of Recommendation E.164 numbering plan for universal international freephone numbers for internationalfreephone service. Recommendation E.164 (05/97) International public telecommunication number for Networks
Principles, criteria and procedures for the assignment of international public telecommunication numbers for inter-national Networks may be found in Recommendations E.164.1 and E.190.
International public telecommunication numbers used by Networks consist of three parts: a shared 3-digit E.164 countrycode; an identification code; and a subscriber number (see Figure 3). The maximum length of international public tele-communication numbers used by Networks is fifteen (15) digits. Country Code for Networks
These digits are the first three digits of international public telecommunication numbers for Networks. A country codefor networks is a shared combination of 3 digits and is used in combination with the Identification Code to identifynetworks. Identification Code
An Identification Code (IC) is a combination of 1 to 4 digits used for identification of Networks. These digits follow theshared country code field within international public telecommunication numbers for Networks. Subscriber Numbers
Subscriber numbers are the remaining digits which follow the shared country code and the IC. The structure andfunctionality is determined by the network operator. The maximum length of the subscriber number is 15 minus, thetotal of the CC and IC digits. Digit analysis
For calls utilizing the international public telecommunication number for Networks, the maximum number of digits to beanalyzed is seven, which includes the three digits of the E.164 country code, the identification code, and the initialsignificant digits (if any) of the subscriber number. A minimum of the 3-digit country code and IC must always beanalyzed to determine the appropriate routing and charging. Escape codes
The use of escape codes shall be in accordance with Recommendation E.166, which describes the use of digit "0" (zero)as an escape code for numbering plan interworking between E.164 and X.121 numbering plans until 31/12/2000 at2359 UTC. International prefix
It is recommended by the ITU-T that the Administrations of countries that have not yet introduced automatic inter-national operation, or Administrations and international network operators that are, for various reasons, defining orrevising their numbering plans, adopt an international prefix (a code for access to the international automatic network)composed of the two digits 004.
In accordance with Recommendation E.123, the symbol "+" is recommended to indicate that an international prefix isrequired.
Where there is a requirement for further discrimination between international network operators and/or the different networkservices they provide, the method for accommodating this need is a national matter. Recommendation E.164 (05/97) Recommendation history
Recommendation E.163, first issue 1964 – revised at all subsequent Plenary Assemblies.
Recommendation E.163 – merged with Recommendation E.164 (see below).
Recommendation E.164, first issue 1984.
Recommendation E.164, second issue 1988.
Recommendation E.164, third issue 1991 – merged with Recommendation E.163.
Recommendation E.164, fourth issue 1997 – incorporates Recommendations E.160 and E.162. Clarification and explanation of the structure and function of E.164 numbers
E.164 numbering is the basis for global addressing in fixed and mobile terminal networks. These numbering
resources uniquely identify user-network interfaces, e.g. PSTN/ISDN, mobile terminals, and individuals utilizingspecific global services, e.g. Universal International Freephone Numbers (UIFNs). Most of the services/subscribers canbe addressed directly, but in cases where indirect addressing is used number translation is required, e.g. for UIFNs.
This Annex provides clarification and explanation to the structure and functionality of E.164 numbers. These
structures/functions are independent of the technical arrangement to record, charge or route the calls. Structure
The international number, which is the foundation of the hierarchy, consists of the country code plus the
necessary additional elements (NDC + SN, GSN or IC + SN). The international public telecommunication number existsonly at the international level, i.e. the CC and GSN are combined to form a single dialling sequence.
In countries where NDC and SN are combined to form a single dialling sequence or where the NDC does not
exist, the local and national levels are integrated and there is no difference between the subscriber number and thenational (significant) number.
E.164 numbers have hierarchical structures as shown in Figure A.1.
When in the local level, typically the use of a national (trunk) prefix provides access to the national level, and
the use of an international prefix provides access to the international level.
Numbers that only exist in the local, intraNetwork and/or national level are not considered E.164 numbers. Number length International number for geographic areas
International numbers for geographic areas have a maximum length of 15 digits.
The maximum length of national (significant) numbers is 15 digits minus the length of the country code.
The maximum length of subscriber numbers is 15 digits minus the length of the country code and the national
Recommendation E.164 (05/97)
International number for geographic areas
NOTE – IntraNetwork level is used when calling and called parties are within the same network. Figure A.1/E.164 – Hierarchical structures of E.164 numbers International number for global services
The maximum length of a global subscriber number is 12 digits since the country code assigned to global services isalways 3 digits in length. International number for Networks
The maximum length of the combined identification code and subscriber number is 12 digits since the country code fornetworks is always 3 digits in length. Summary of number length
Table A.1 summarizes the maximum number length on each level for the three categories of international numbers. Recommendation E.164 (05/97) Table A.1/E.164 – Maximum number length Geographic areas Global services Networks Unique identification of international number for geographic areas
An international number for geographic areas uniquely identifies a subscriber within a geographical area
locally, nationally and internationally, i.e. dialling the subscriber number locally, the national (significant) numbernationally and the international number internationally always provides identification of the same subscriber.
The national (significant) number provides unique identification of one subscriber irrespective of where the
call is generated from within the country or geographical area characterized by CC.
The subscriber number provides unique identification of one subscriber irrespective of where the call is
generated from within a local area identified by NDC, where applicable. The subscriber number is a complete numberand can therefore not be separated.
Use of prefixes to distinguish the national (significant) number and the international number from the
subscriber number does not alter the uniqueness of E.164 numbers. Unique identification of international number for global services
The international number for global services uniquely identifies subscribers only at the international level. The inter-national number for global services is a complete number, and can therefore not be separated. Unique identification of international number for Networks
For illustrative purposes only, it is assumed that intraNetwork dialling is by subscriber number.
An international number for Networks uniquely identifies a subscriber within a Network, and internationally,
i.e. dialling the subscriber number and the international number, always provides identification of the same subscriber.
The subscriber number provides unique identification of one subscriber irrespective of where the call is
generated from within the Network identified by CC + IC. The subscriber number is a complete number and cantherefore not be separated.
Use of an international prefix to distinguish the subscriber number and the international number for Networks
does not alter the uniqueness of E.164 numbers. Non-E.164 numbers
Any international number for geographical areas, global services or Networks which does not conform to the
structure, length and uniqueness as defined in this Annex or in the main body of this Recommendation is not an E.164number.
Non-E.164 numbers may not be passed across any Network boundaries without a specific bilateral agreement.
Listed below are some examples of non-E.164 numbers from the first category of numbers. These examples
Recommendation E.164 (05/97) Local special numbers
For example Local Special Numbers (LSPNs) with significantly fewer digits than subscriber numbers, and which arevalid for a specific purpose only, within a limited part of the same NDC area.
The LSPNs are part of a hierarchical structure with three levels as follows:
Since LSPNs are significantly shorter than the subscriber numbers, they are within the limits of Table A.1.
If LSPNs and NDC + LSPN terminate at the same service then LSPN would be an E.164 number, but this is not the casein this example. In our example the LSPN terminates at, for instance, two different services within the NDC area,depending upon from where the calling user is located. LSPN and NDC + LSPN are ambiguous and therefore not E.164numbers. International special numbers used nationally
In this example, the International Special Numbers (ISPNs) are numbers with significantly fewer digits than ordinarysubscriber numbers, and which only exist in an international format within the country which provides it. The digits ofISPN are identical to the leading digits of one or more subscriber numbers.
Nationally, the ISPNs exist only at the international level as follows:
Since ISPNs are significantly shorter than the subscriber numbers, they are within the limits of Table A.1.
Nationally the CC + NDC + ISPN could terminate at a service center. As the digits of ISPN are identical to the leadingdigits of a subscriber number, all incoming international calls to the service center will fail because the CC + NDC +ISPN and the leading digits of CC + NDC + SN are ambiguous, and therefore not E.164 numbers. Network specific numbers
In this example network specific numbers are numbers that belong to subscribers connected to one network operator in acountry with more than one operator, but where the network operator demands that the calling user dials some additionaldigits.
The network specific numbers have a hierarchical structure with 3 levels as follows:
NOTE – ADs (Additional Digits) are the network operator identification digits that would have to be added by the calling usersabroad to remove ambiguity and reach a particular subscriber in specific national network.
The international number does not fit in the hierarchical structure because it consists of more than the country code plusthe national (significant) number. AD is not part of the national (significant) number, but may be part of a national prefixused to distinguish the national (significant) numbers from the subscriber numbers.
The numbers are not unique because NDC + SN and CC + NDC + SN lead to two different subscribers.
Network-specific numbers that are manipulated in this way are not E.164 numbers. National (significant) numbers with excessive length
In this example, the national (significant) numbers (NDC + SN) as used nationally have differing lengths, and thelongest national (significant) numbers violate the maximum given in Table A.1. Recommendation E.164 (05/97)
The numbers have a hierarchical structure as follows. The structure is independent of the number length.
Some of the national (significant) numbers (NDC + SN) and international numbers (CC + NDC + SN) are longer thanthe maximum given in Table A.1. These numbers are not E.164 numbers. The most significant part of the national(significant) numbers, truncated to the limits given in Table A.1, are E.164 numbers provided that they are unique. Application of international public telecommunication numbers for ISDN
This Annex describes the application of international public telecommunication numbers to ISDN numbering andaddressing. Additional numbering and addressing requirements are covered in separate Recommendations, e.g. B-ISDNis contained in Recommendation E.191. ISDN numbers
Numbering for ISDN is an integral part of the international public telecommunication numbering plan.
The ISDN number is an application of international public telecommunication numbering for geographic areas and forinternational networks, to the ISDN user-network interface/network termination. Addressing Identification
Identification within a subscriber’s installation of a point beyond the ISDN boundary requires the transfer of addressinformation from the public network to the subscriber’s equipment. Two cases can apply:
identification by an ISDN number plus additional address information. Addressing by an ISDN number
When selecting a destination in the subscriber installation, digits forming the end of the ISDN subscriber number aretransferred to the called subscriber’s installation as a partial number (see Figure B.1). The number of digits used dependsupon the requirements of the called subscriber’s equipment and the capacity of the numbering plan used.
In instances where a partial number is utilized, e.g. Network Termination 2 (NT2), the number will be used in thecontext of the direct-dialling-in supplementary service.
If the subscriber’s installation consists of terminal equipment only, the transferred digits will be used in the context ofthe multiple-subscriber-number supplementary service. Recommendation E.164 (05/97)
NOTE – The multiple-subscriber-number application is not covered in the diagram. Figure B.1/E.164 Sub-addressing (network address extension)
Sub-addressing provides an additional addressing capacity outside the ISDN numbering plan but constitutes an intrinsicpart of the ISDN addressing capabilities. The sub-address is a sequence of digits, following the ISDN number. Themaximum length should be 20 octets (40 digits). As shown in Figure B.1, the sub-address may follow the ISDN numberand form the ISDN address, which is transferred to the equipment at the subscriber’s premises.
When required, the sub-address is sent by the calling party within the call set-up procedure and is passed transparentlythrough the network as a separate entity from both the ISDN number and user-to-user information. Sub-addressinformation is not required to be processed within the public network. Combination of addressing and sub-addressing
Sub-addressing may be used separately or in combination with a partial number (see Figure B.1). Dialling procedures
The subscriber dialling procedures for local, national and international calls shall be in accordance with
clause 7. However, subscriber’s control procedures for supplementary services will be as defined in RecommendationE.131 or in separate Recommendations for each service.
ISDN subscribers will always be called by the same subscriber number irrespective of where in the public
network the call originates. For calls in the same numbering area or local network, the subscriber number alone isdialled. For national calls between numbering areas or local networks, the subscriber number may be preceded by thenational prefix and the national destination code.
The addressing procedures for calls using sub-addressing are described in B.3. Network identification Geographic areas
In countries served by more than one ISDN and/or Public Switched Telephone Network (PSTN), the networkidentification of each is a national matter. Recommendation E.164 (05/97)
Network identification within the national (significant) number shall be such that:
in a country all destination ISDN and PSTN networks shall operate under a single country code;
the international number maximum length of 15 digits shall not be exceeded, nor shall it be necessary for thenumber of digits for number analysis to exceed that specified in 7.5;
provision of network identification is not mandatory for countries using a single integrated numbering planarrangement for their ISDNs and PSTNs. Networks
In all cases when Network codes are assigned, they are supplemented with Identification Codes (ICs) which uniquelyidentify each international Network.
Digit analysis of the CC + IC provides the required network identification. Service parameters
The ISDN number by itself will not identify the particular nature of the service, which is derived from particularsignalling parameters that are not part of the numbering plan. For example, for ISDN calls, in addition to a number andpossible prefix, there is a requirement to provide a choice of bearer capability in the signalling protocol. One number cantherefore facilitate access to more than one service. Calling/connected line identity
Calling/Connected Line Identity (CLI/COLI) is address information which is passed across the network to providesupplementary services such as calling (or connected) line identification presentation. The format of the CLI and COLIfor international calls should be the full international number, i.e. Country Code (CC), National Destination Code (NDC)and Subscriber Number (SN). No other information, such as prefixes or symbols (e.g. "+"), should be included, althougha sub-address may be associated with the CLI/COLI. However, in a country where network-specific numbers are utilizedfor identifying customers or network services it remains a national matter. When implemented, the NPI (Numbering PlanIdentifier) TON (Type of Number) mechanism should define the numbering status of the calling/connected line. Theauthorization to pass CLI/COLI across an international boundary is a national matter. Recommendation E.164 (05/97) ITU-T RECOMMENDATIONS SERIES
Means of expression: definitions, symbols, classification
Overall network operation, telephone service, service operation and human factors
Transmission systems and media, digital systems and networks
Transmission of television, sound programme and other multimedia signals
Construction, installation and protection of cables and other elements of outsideplant
TMN and network maintenance: international transmission systems, telephonecircuits, telegraphy, facsimile and leased circuits
Maintenance: international sound programme and television transmission circuits
Telephone transmission quality, telephone installations, local line networks
Data communication over the telephone network
Data networks and open system communication
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