1、INTERNATIONAL TELECOMMUNICATION UNIONITU-T X.121TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU(10/2000)SERIES X: DATA NETWORKS AND OPEN SYSTEMCOMMUNICATIONSPublic data networks Network aspectsInternational numbering plan for public datanetworksITU-T Recommendation X.121(Formerly CCITT Recommendation)
2、ITU-T X-SERIES RECOMMENDATIONSDATA NETWORKS AND OPEN SYSTEM COMMUNICATIONSPUBLIC DATA NETWORKSServices and facilities X.1X.19Interfaces X.20X.49Transmission, signalling and switching X.50X.89Network aspects X.90X.149Maintenance X.150X.179Administrative arrangements X.180X.199OPEN SYSTEMS INTERCONNEC
3、TIONModel and notation X.200X.209Service definitions X.210X.219Connection-mode protocol specifications X.220X.229Connectionless-mode protocol specifications X.230X.239PICS proformas X.240X.259Protocol Identification X.260X.269Security Protocols X.270X.279Layer Managed Objects X.280X.289Conformance t
4、esting X.290X.299INTERWORKING BETWEEN NETWORKSGeneral X.300X.349Satellite data transmission systems X.350X.369IP-based networks X.370X.399MESSAGE HANDLING SYSTEMS X.400X.499DIRECTORY X.500X.599OSI NETWORKING AND SYSTEM ASPECTSNetworking X.600X.629Efficiency X.630X.639Quality of service X.640X.649Nam
5、ing, Addressing and Registration X.650X.679Abstract Syntax Notation One (ASN.1) X.680X.699OSI MANAGEMENTSystems Management framework and architecture X.700X.709Management Communication Service and Protocol X.710X.719Structure of Management Information X.720X.729Management functions and ODMA function
6、s X.730X.799SECURITY X.800X.849OSI APPLICATIONSCommitment, Concurrency and Recovery X.850X.859Transaction processing X.860X.879Remote operations X.880X.899OPEN DISTRIBUTED PROCESSING X.900X.999For further details, please refer to the list of ITU-T Recommendations.ITU-T X.121 (10/2000) iITU-T Recomme
7、ndation X.121International numbering plan for public data networksSummaryThis Recommendation defines the design, characteristics and application of the Numbering Plan forPublic Data Networks. The International Numbering Plan for Public Data Networks has beendeveloped in order to facilitate the opera
8、tion of public data networks and provide for theirinterworking on a worldwide basis. The numbering plan allows for the identification of a country aswell as a specific public data network in that country by means of Data Country Codes and DataNetwork Identification Codes. Additionally the numbering
9、plan also allows for the identification ofGlobal public data networks by means of a Global Data Network Identification Code. Interworkingwith other numbering plans can be achieved by use of an escape code mechanism.In order to conserve the valuable numbering resource, guidance is provided on the eff
10、icient use ofData Country codes for the creation of Data Network Identification Codes, and on the use of variablelength Private Network Identification Codes for the numbering of private data networks in harmonywith the Public Network Numbering Plan. Procedures for the allocation of Data Country Code
11、s aredefined. The eligibility criteria and procedures for the allocation of Data Network IdentificationCodes to Global public data networks are also defined. Guidance is also provided on the numberingof global networks.SourceITU-T Recommendation X.121 was revised by ITU-T Study Group 7 (1997-2000) a
12、nd approved bythe World Telecommunication Standardization Assembly (Montreal, 27 September 6 October 2000).ii ITU-T X.121 (10/2000)FOREWORDThe International Telecommunication Union (ITU) is the United Nations specialized agency in the field oftelecommunications. The ITU Telecommunication Standardiza
13、tion Sector (ITU-T) is a permanent organ ofITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendationson them with a view to standardizing telecommunications on a worldwide basis.The World Telecommunication Standardization Assembly (WTSA), which meets
14、 every four years,establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on thesetopics.The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.In some areas of information technology which fall within ITU-Ts purvie
15、w, the necessary standards areprepared on a collaborative basis with ISO and IEC.NOTEIn this Recommendation, the expression “Administration“ is used for conciseness to indicate both atelecommunication administration and a recognized operating agency.INTELLECTUAL PROPERTY RIGHTSITU draws attention to
16、 the possibility that the practice or implementation of this Recommendation mayinvolve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence,validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or othersoutside o
17、f the Recommendation development process.As of the date of approval of this Recommendation, ITU had not received notice of intellectual property,protected by patents, which may be required to implement this Recommendation. However, implementors arecautioned that this may not represent the latest inf
18、ormation and are therefore strongly urged to consult theTSB patent database. ITU 2001All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means,electronic or mechanical, including photocopying and microfilm, without permission in writing from ITU.ITU-T
19、 X.121 (10/2000) iiiCONTENTSPage1 Introduction 12 Scope 13 References 14 Definitions 25 Abbreviations . 26 Design considerations. 37 Characteristics and application of the Numbering Plan . 37.1 Number system. 37.2 Data network identification codes and data country codes 47.3 Procedures for the alloc
20、ation of Data Country Codes and assignment of NetworkDigits 57.3.1 Procedures for the allocation of Data Country Codes. 57.3.2 Assignment of Network Digits 67.4 Data Network Identification Codes for public mobile satellite systems 67.5 Data Network Identification Codes for Global Public Data Network
21、s 67.6 International data number. 67.7 Number of digits. 77.8 Prefixes. 77.9 Escape codes for number plan interworking 87.10 Numbering plan interworking 87.11 Private data Network Identification Codes (PNICs) 87.12 Number analysis International calls between public data networks 97.13 Directories an
22、d letterheads . 10Annex A Procedures for the allocation of data country codes and assignment ofnetwork digits . 12A.1 Procedures for the allocation of Data Country Codes 12A.2 Assignment of Network Digits. 12Annex B Development of data network identification codes. 13Annex C Recommendations for the
23、efficient use of DCCs to create DNICs. 14Annex D Use of Private data Network Identification Codes (PNICs) for thedevelopment of network terminal numbers for a group of public data networksor for a group of private data networks connected to public data networks. 15Annex E Guidelines for the structur
24、e of variable length PNICs 16E.1 Introduction 16iv ITU-T X.121 (10/2000)PageE.2 Structure of the “PNIC specific“ DNIC number space. 17E.3 PNIC eligibility criteria 17E.4 Variable length PNIC structures. 18Annex F Guidelines on Numbering of Private Data Networks: Use of PNIC structurefor private X.25
25、 networks not attached to the PSPDN. 19Annex G Eligibility criteria and procedures for the allocation of DNICs to globalpublic data networks. 20G.1 General guidelines 20G.2 Eligibility criteria 20G.3 Procedures for the allocation of DNICs to global networks. 22G.4 Reclamation of Global DNICS. 22Anne
26、x H Guidelines for the numbering of global networks 23Annex I List of DNICs allocated to public mobile satellite systems and globalpublic data networks. 25Annex J List of data country or geographical area codes. 25Annex K Definitions regarding the international numbering plan for public datanetworks
27、 . 33Annex L Notification of the assignment of Data Network Identification Codes . 34ITU-T X.121 (10/2000) 1ITU-T Recommendation X.121International numbering plan for public data networks1 IntroductionThis Recommendation defines the design, characteristics and application of the Numbering Plan forPu
28、blic Data Networks. The International Numbering Plan has been developed in order to facilitatethe operation of public data networks and provide for their interworking on a worldwide basis. Thenumbering plan allows for a number of public data networks in a country; the identification of acountry as w
29、ell as a specific public data network in that country; and a mechanism (use of escapecodes) for interworking with other numbering plans.2ScopeThe scope of this Recommendation is to describe the form and function of the InternationalNumbering Plan for Public Data Networks. In order to conserve the va
30、luable numbering resource,guidance is also given on methods for the efficient use of Data Country Codes to create DataNetwork Identification Codes, the numbering of private data networks and the use of variable lengthPrivate Network Identification Codes. Procedures for the allocation of Data Country
31、 codes aredefined. Eligibility criteria and procedures for the allocation of Data Network Identification Codes toGlobal public data networks are provided.3 ReferencesThe following ITU-T Recommendations and other references contain provisions, which, throughreference in this text, constitute provisio
32、ns of this Recommendation. At the time of publication, theeditions indicated were valid. All Recommendations and other references are subject to revision;users of this Recommendation are therefore encouraged to investigate the possibility of applying themost recent edition of the Recommendations and
33、 other references listed below. A list of the currentlyvalid ITU-T Recommendations is regularly published. ITU-T E.164 (1997), The international public telecommunication numbering plan. ITU-T E.165 (1988), Timetable for coordinated implementation of the full capability of thenumbering plan for the I
34、SDN era (Recommendation E.164). ITU-T E.165.1 (1996), Use of escape code “0“ within the E.164 numbering plan during thetransition period to implementation of NPI mechanism. ITU-T E.166/X.122 (1998), Numbering plan interworking for the E.164 and X.121numbering plans. ITU-T E.215 (1997), Telephone/ISD
35、N numbering plan for the mobile-satellite services ofInmarsat. ITU-T F.69 (1994), The international telex service Service and operational provisions oftelex destination codes and telex network identification codes. ITU-T F.125 (1993), Numbering plan for access to the mobile-satellite services ofINMA
36、RSAT from the international telex service. ITU-T I.330 (1988), ISDN numbering and addressing principles.2 ITU-T X.121 (10/2000) ITU-T X.25 (1996), Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in packet mode and connected topubli
37、c data networks by dedicated circuit. ITU-T X.28 (1997), DTE/DCE interface for a start-stop mode Data Terminal Equipmentaccessing the Packet Assembly/Disassembly facility (PAD) in a public data network situatedin the same country. ITU-T X.32 (1996), Interface between Data Terminal Equipment (DTE) an
38、d Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and accessing aPacket-Switched Public Data Network through a public switched telephone network or anIntegrated Services Digital Network or a Circuit Switched Public Data Network. ITU-T X.36 (2000), Interface betwee
39、n Data Terminal Equipment (DTE) and DataCircuit-Terminating Equipment (DCE) for public data networks providing frame relay datatransmission service by dedicated circuit. ITU-T X.75 (1996), Packet-switched signalling system between public networks providingdata transmission services. ITU-T X.76 (2000
40、), Network-to-network interface between public networks providing PVCand/or SVC frame relay data transmission service. ITU-T X.123 (1996), Mapping between escape codes and TOA/NPI for E.164/X.121numbering plan interworking during the transition period. ITU-T X.124 (1999), Arrangements for the interw
41、orking of the E.164 and X.121 numberingplans for frame relay and ATM Networks.4 DefinitionsWithin the public switched telephone and public data network environment, the terms used for allnetworks and services must be compatible and consistent. Therefore this Recommendation, inaddition to the terms d
42、efined herein, relies on a list of terms and definitions contained in E.164.Additionally, the terms and their applicability to number plan interworking can be found inE.166/X.122. A list of definitions is given in Annex K.5 AbbreviationsThis Recommendation uses the following abbreviations.ATM Asynch
43、ronous Transfer ModeCC Country CodeDCC Data Country CodeDCE Data Circuit-terminating EquipmentDNIC Data Network Identification CodeDTE Data Terminal EquipmentFR Frame RelayISDN Integrated Services Digital NetworkITU-T International Telecommunication Union Telecommunication Standardization SectorNN N
44、ational NumberNPI Numbering Plan IdentifierITU-T X.121 (10/2000) 3NTN Network Terminal NumberPDN Public Data NetworkPNIC Private data Network Identification CodePSPDN Packet Switched Public Data NetworkPSTN Public Switched Telephone NetworkROA Recognized Operating AgencyTDC Telex Destination CodeTOA
45、 Type Of AddressTON Type Of NumberTSB Telecommunication Standardization Bureau6 Design considerationsThe general design considerations that form the basis of this Numbering Plan are as follows:a) The international data number is used to identify a country, a particular network, if severaldata networ
46、ks exist in the same country, and a specific data terminal equipment/datacircuit-terminating equipment (DTE/DCE) interface on that network.b) Where a number of public data networks are to be established in a country, it should not bemandatory to integrate the numbering plans of the various networks.
47、c) The number of digits comprising the code used to identify a country and a specific publicdata network in that country should be a fixed number of digits and should be the same forall countries.d) A national data number assigned to a DTE/DCE interface should be unique within aparticular national n
48、etwork. This national data number should form part of the internationaldata number which should also be unique on a worldwide basis.e) The number of digits to be used in an international data number should be governed bynational and international requirements and a reasonable limit on the overall nu
49、mber ofdigits should be imposed.f) The Numbering Plan should make provision for the interworking of data terminals on publicdata networks (e.g. X.25) with data terminals on public telephone and telex networks and onIntegrated Services Digital Networks (ISDNs).g) The Numbering Plan should not preclude the possibility of a single national networkproviding an integrated telecommunications system for services of all kinds.7 Characteristics and application of the Numbering Plan7.1 Number systemThe 10-digit numeric
