ITU-T X.121(10 2000) International numbering plan

INTERNATIONALTELECOMMUNICATIONUNIONX.121TELECOMMUNICATIONSTANDARDIZATIONSECTOROFITU(10/2000)SERIESX:DATANETWORKSANDOPENSYSTEMCOMMUNICATIONSPublicdatanetworks–NetworkaspectsInternationalnumberingplanforpublicdatanetworksITU-TRecommendationX.121(FormerlyCCITTRecommendation)ITU-TX-SERIESRECOMMENDATIONSDATANETWORKSANDOPENSYSTEMCOMMUNICATIONSPUBLICDATANETWORKSServicesandfacilitiesX.1–X.19InterfacesX.20–X.49Transmission,signallingandswitchingX.50–X.89NetworkaspectsX.90–X.149MaintenanceX.150–X.179AdministrativearrangementsX.180–X.199OPENSYSTEMSINTERCONNECTIONModelandnotationX.200–X.209ServicedefinitionsX.210–X.219Connection-modeprotocolspecificationsX.220–X.229Connectionless-modeprotocolspecificationsX.230–X.239PICSproformasX.240–X.259ProtocolIdentificationX.260–X.269SecurityProtocolsX.270–X.279LayerManagedObjectsX.280–X.289ConformancetestingX.290–X.299INTERWORKINGBETWEENNETWORKSGeneralX.300–X.349SatellitedatatransmissionsystemsX.350–X.369IP-basednetworksX.370–X.399MESSAGEHANDLINGSYSTEMSX.400–X.499DIRECTORYX.500–X.599OSINETWORKINGANDSYSTEMASPECTSNetworkingX.600–X.629EfficiencyX.630–X.639QualityofserviceX.640–X.649Naming,AddressingandRegistrationX.650–X.679AbstractSyntaxNotationOne(ASN.1)X.680–X.699OSIMANAGEMENTSystemsManagementframeworkandarchitectureX.700–X.709ManagementCommunicationServiceandProtocolX.710–X.719StructureofManagementInformationX.720–X.729ManagementfunctionsandODMAfunctionsX.730–X.799SECURITYX.800–X.849OSIAPPLICATIONSCommitment,ConcurrencyandRecoveryX.850–X.859TransactionprocessingX.860–X.879RemoteoperationsX.880–X.899OPENDISTRIBUTEDPROCESSINGX.900–X.999Forfurtherdetails,pleaserefertothelistofITU-TRecommendations.ITU-TX.121(10/2000)iITU-TRecommendationX.121InternationalnumberingplanforpublicdatanetworksSummaryThisRecommendationdefinesthedesign,characteristicsandapplicationoftheNumberingPlanforPublicDataNetworks.TheInternationalNumberingPlanforPublicDataNetworkshasbeendevelopedinordertofacilitatetheoperationofpublicdatanetworksandprovidefortheirinterworkingonaworldwidebasis.ThenumberingplanallowsfortheidentificationofacountryaswellasaspecificpublicdatanetworkinthatcountrybymeansofDataCountryCodesandDataNetworkIdentificationCodes.AdditionallythenumberingplanalsoallowsfortheidentificationofGlobalpublicdatanetworksbymeansofaGlobalDataNetworkIdentificationCode.Interworkingwithothernumberingplanscanbeachievedbyuseofanescapecodemechanism.Inordertoconservethevaluablenumberingresource,guidanceisprovidedontheefficientuseofDataCountrycodesforthecreationofDataNetworkIdentificationCodes,andontheuseofvariablelengthPrivateNetworkIdentificationCodesforthenumberingofprivatedatanetworksinharmonywiththePublicNetworkNumberingPlan.ProceduresfortheallocationofDataCountryCodesaredefined.TheeligibilitycriteriaandproceduresfortheallocationofDataNetworkIdentificationCodestoGlobalpublicdatanetworksarealsodefined.Guidanceisalsoprovidedonthenumberingofglobalnetworks.SourceITU-TRecommendationX.121wasrevisedbyITU-TStudyGroup7(1997-2000)andapprovedbytheWorldTelecommunicationStandardizationAssembly(Montreal,27September−6October2000).iiITU-TX.121(10/2000)FOREWORDTheInternationalTelecommunicationUnion(ITU)istheUnitedNationsspecializedagencyinthefieldoftelecommunications.TheITUTelecommunicationStandardizationSector(ITU-T)isapermanentorganofITU.ITU-Tisresponsibleforstudyingtechnical,operatingandtariffquestionsandissuingRecommendationsonthemwithaviewtostandardizingtelecommunicationsonaworldwidebasis.TheWorldTelecommunicationStandardizationAssembly(WTSA),whichmeetseveryfouryears,establishesthetopicsforstudybytheITU-Tstudygroupswhich,inturn,produceRecommendationsonthesetopics.TheapprovalofITU-TRecommendationsiscoveredbytheprocedurelaiddowninWTSAResolution1.InsomeareasofinformationtechnologywhichfallwithinITU-T'spurview,thenecessarystandardsarepreparedonacollaborativebasiswithISOandIEC.NOTEInthisRecommendation,theexpressionAdministrationisusedforconcisenesstoindicatebothatelecommunicationadministrationandarecognizedoperatingagency.INTELLECTUALPROPERTYRIGHTSITUdrawsattentiontothepossibilitythatthepracticeorimplementationofthisRecommendationmayinvolvetheuseofaclaimedIntellectualPropertyRight.ITUtakesnopositionconcerningtheevidence,validityorapplicabilityofclaimedIntellectualPropertyRights,whetherassertedbyITUmembersorothersoutsideoftheRecommendationdevelopmentprocess.AsofthedateofapprovalofthisRecommendation,ITUhadnotreceivednoticeofintellectualproperty,protectedbypatents,whichmayberequiredtoimplementthisRecommendation.However,implementorsarecautionedthatthismaynotrepresentthelatestinformationandarethereforestronglyurgedtoconsulttheTSBpatentdatabase.
ITU2001Allrightsreserved.Nopartofthispublicationmaybereproducedorutilizedinanyformorbyanymeans,electronicormechanical,includingphotocopyingandmicrofilm,withoutpermissioninwritingfromITU.ITU-TX.121(10/2000)iiiCONTENTSPage1Introduction.................................................................................................................12Scope............................................