SIST EN 301 141-1 V2.1.1:2005
(Main)Integrated Services Digital Network (ISDN); Narrowband Multi-service Delivery System (NMDS); Part 1: NMDS interface specification
General Information
- Abstract
To clearify following items: 1) B-channel selection, 2) usage of STATUS/ENQUIRY message, 3) call collision.
- Status
- Published
- Publication Date
- 31-Dec-2004
- Technical Committee
- SPN - Services and Protocols for Networks
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Jan-2005
- Due Date
- 01-Jan-2005
- Completion Date
- 01-Jan-2005
Overview
SIST EN 301 141-1 V2.1.1:2005 specifies the interface requirements for the Narrowband Multi-service Delivery System (NMDS) within Integrated Services Digital Networks (ISDN). The primary aim of this standard is to enable the delivery of both Public Switched Telephone Network (PSTN) and ISDN services over an ISDN Basic Access (ISDN-BA) digital subscriber line (DSL) using a unified interface. The standard, endorsed by SIST and aligned with EN 301 141-1, clarifies crucial aspects such as B-channel selection, the use of STATUS/ENQUIRY messages, and call collision scenarios to ensure smooth multi-service delivery.
Key Topics
- NMDS Interface Specification: Details the requirements for connecting NMDS interfaces via a Network Termination Node (NTN) to Local Exchanges (LE) or through an Access Network (AN) using V5 interfaces.
- B-channel Selection: Outlines procedures for selecting bearer channels, allowing efficient allocation and management of available B-channels for both PSTN and ISDN services.
- STATUS/ENQUIRY Messages: Introduces enhanced maintenance messaging for the monitoring and management of user ports and synchronization state, ensuring system reliability.
- Call Collision Handling: Provides guidance for resolving simultaneous call setup attempts to optimize network performance and prevent service conflicts.
- PSTN and ISDN Coexistence: Supports both analog PSTN and digital ISDN user ports via the same physical infrastructure.
- Layer Specifications: Defines functions across physical (Layer 1), data link (Layer 2), and network (Layer 3) layers, focusing on activation, maintenance, error handling, and diagnostic procedures.
Applications
The practical value of SIST EN 301 141-1 V2.1.1:2005 lies in enabling telecommunications operators and equipment manufacturers to:
- Integrate PSTN and ISDN Services: Deliver multiple voice and data services over a single ISDN-BA DSL connection for residential and business users, reducing infrastructure complexity.
- Simplify Customer Premises Equipment (CPE): Allow traditional telephone (PSTN) and ISDN devices to connect seamlessly using Terminal Adapters (TAs) and unified subscriber interfaces.
- Maintain Service Quality: Use standardized maintenance and status enquiry procedures for proactive monitoring and rapid fault diagnosis, leading to improved reliability and customer satisfaction.
- Support Network Evolution: Ensure backward compatibility and smooth transition paths for legacy PSTN services as networks migrate to newer digital access technologies.
- Optimize Resource Allocation: Implement precise B-channel selection to maximize the utilization of available channel resources, thereby supporting multi-call scenarios and supplementary features.
Typical implementation scenarios include multi-dwelling units, office buildings, and remote concentrators where efficient delivery of both analog and digital services is essential. The clarified procedures for B-channel allocation and collision handling are especially useful in high-density or converged network environments.
Related Standards
Organizations implementing SIST EN 301 141-1 V2.1.1:2005 should also consider the following standards for a complete compliance and interoperability framework:
- EN 301 141-2: Protocol Implementation Conformance Statement (PICS) proforma specification for NMDS.
- EN 301 141-3/4: Defines test suite structure, test purposes, and conformance testing for the NMDS interface.
- ETSI ETS 300 012-1: Layer 1 specification for ISDN Basic User-Network Interface.
- ETSI ETS 300 324-1 and ETS 300 347-1: V5.1 and V5.2 interface specifications for Access Networks.
- ETSI ETS 300 402-2: Data link layer protocol for the DSS1 protocol.
- ITU-T I.412: ISDN user-network interface structures.
These related standards provide complementary requirements for interface protocols, system conformance, and support seamless interoperability across Europe’s digital telecommunication networks.
Keywords: ISDN, PSTN, NMDS, B-channel selection, STATUS message, ENQUIRY message, call collision, digital subscriber line, network termination node, maintenance, interface specification, telecommunication standard.
Get Certified
Connect with accredited certification bodies for this standard
ANCE
Mexican certification and testing association.
Intertek Slovenia
Intertek testing, inspection, and certification services in Slovenia.
LNE (Laboratoire National de Métrologie et d'Essais)
French national laboratory for metrology and testing.
Sponsored listings
Frequently Asked Questions
SIST EN 301 141-1 V2.1.1:2005 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Integrated Services Digital Network (ISDN); Narrowband Multi-service Delivery System (NMDS); Part 1: NMDS interface specification". This standard covers: To clearify following items: 1) B-channel selection, 2) usage of STATUS/ENQUIRY message, 3) call collision.
To clearify following items: 1) B-channel selection, 2) usage of STATUS/ENQUIRY message, 3) call collision.
SIST EN 301 141-1 V2.1.1:2005 is classified under the following ICS (International Classification for Standards) categories: 33.080 - Integrated Services Digital Network (ISDN). The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 301 141-1 V2.1.1:2005 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Integrated Services Digital Network (ISDN); Narrowband Multi-service Delivery System (NMDS); Part 1: NMDS interface specification33.080Digitalno omrežje z integriranimi storitvami (ISDN)Integrated Services Digital Network (ISDN)ICS:Ta slovenski standard je istoveten z:EN 301 141-1 Version 2.1.1SIST EN 301 141-1 V2.1.1:2005en01-januar-2005SIST EN 301 141-1 V2.1.1:2005SLOVENSKI
STANDARD
ETSIEN301141-1V2.1.1(2000-11)EuropeanStandard(Telecommunicationsseries)IntegratedServicesDigitalNetwork(ISDN);NarrowbandMulti-serviceDeliverySystem(NMDS);Part1:NMDSinterfacespecificationSIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)2ReferenceREN/SPAN-09103-1Keywordsaccess,basic,ISDN,NMDS,PSTNETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:+33492944200Fax:+33493654716SiretN°34862356200017-NAF742CAssociationàbutnonlucratifenregistréeàlaSous-PréfecturedeGrasse(06)N°7803/88ImportantnoticeIndividualcopiesofthepresentdocumentcanbedownloadedfrom:http://www.etsi.orgThepresentdocumentmaybemadeavailableinmorethanoneelectronicversionorinprint.Inanycaseofexistingorperceiveddifferenceincontentsbetweensuchversions,thereferenceversionisthePortableDocumentFormat(PDF).Incaseofdispute,thereferenceshallbetheprintingonETSIprintersofthePDFversionkeptonaspecificnetworkdrivewithinETSISecretariat.Usersofthepresentdocumentshouldbeawarethatthedocumentmaybesubjecttorevisionorchangeofstatus.InformationonthecurrentstatusofthisandotherETSIdocumentsisavailableathttp://www.etsi.org/tb/status/Ifyoufinderrorsinthepresentdocument,sendyourcommentto:editor@etsi.frCopyrightNotificationNopartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2000.Allrightsreserved.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)3ContentsIntellectualPropertyRights.5Foreword.5Introduction.51Scope.62References.63Definitionsandabbreviations.73.1Definitions.73.2Abbreviations.74Generaldescription.85Layer1functions.85.1PoweringAspects.95.1.1Poweravailablefromthetransmissionsystem.95.1.2NMDSbehaviourunderpowerfailconditions.96Layer2functions.106.1Overview.106.2PSTN-GWlayer2statemachinemodifications.116.3PSTNlayer2activation.117Layer3functionsandmessagedefinitions.127.1General.127.2Errorhandling.127.3Maintenancefunctions.127.3.1ThenewSTATUSENQUIRYandSTATUSmessages.137.3.1.1PSTNmaintenancemessages.137.3.1.1.1TheMAINTENANCESTATUSENQUIRYmessageforPSTNmaintenance.137.3.1.1.2TheMAINTENANCESTATUSmessageforPSTNmaintenance.137.3.1.2ISDNmaintenancemessages.147.3.1.2.1TheMAINTENANCESTATUSENQUIRYmessageforISDNmaintenance.157.3.1.2.2TheMAINTENANCESTATUSmessageforISDNmaintenance.157.3.2Maintenancestatusprocedure.167.3.2.1Normaloperation.167.3.2.2Exceptionalprocedures.167.3.2.2.1NTN.177.3.2.2.2LE.177.3.2.3TimerTmdefinition.178B-channelselectionprocedure.188.1Introduction.188.2B-channelselection.188.2.1LEFunctionality.188.2.1.1GeneralRequirements.188.2.1.1.1HandlingofvalidL3addrvalues.188.2.1.1.2HandlingofinvalidL3addrvalues.198.2.1.2SpecificRequirementsforPSTNCalls.198.2.2NTNFunctionality.198.2.2.1Generalrequirements.198.2.2.2SpecificRequirementsforPSTNCalls.20SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)4AnnexA(informative):B-channelselection.21A.1General.21A.2Outgoingcalls(NTNtoLE).21A.3Callclearing.22A.4Incomingcalls(LEtoNTN).22A.5PSTN-GWparkedstate.23A.6Clearingfromparkedstate.24A.7Outgoingcalls(NTNtoLE)withdelayedB-channelselection.25AnnexB(informative):BackgroundandmotivationforNMDS.26B.1Transparentsupplementaryserviceoperation.26B.2Operationalbenefits.26AnnexC(informative):ThePSTNprotocoladoptedfortheNMDS.27C.1TheV5PSTNprotocol.27AnnexD(informative):TherelationshipbetweenadirectlyconnectedNMDSandonesupportedviaanaccessnetwork.28D.1Introduction.28AnnexE(informative):Thereasonsforthenewinformationelementvalueschosen.32E.1General.32E.2SpecificcodingrulesforinformationelementsintheV5specifications.32E.3SpecificcodesusedfortheSTATUSENQUIRYinformationelementsforNMDS.32E.4SpecificcodesusedfortheSTATUSinformationelementsforNMDS.32AnnexF(informative):Permanentactivationofbasicaccessdigitalsection.33AnnexG(informative):Remoteequipment-functionalrequirements.34AnnexH(informative):SupplementaryservicesuseableattheNMDS.37H.1ApplicabilityofPSTNsupplementaryservices.37H.2ApplicabilityofISDNsupplementaryservices.37Bibliography.38History.39SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)5IntellectualPropertyRightsIPRsessentialorpotentiallyessentialtothepresentdocumentmayhavebeendeclaredtoETSI.TheinformationpertainingtotheseessentialIPRs,ifany,ispubliclyavailableforETSImembersandnon-members,andcanbefoundinETSISR000314:"IntellectualPropertyRights(IPRs);Essential,orpotentiallyEssential,IPRsnotifiedtoETSIinrespectofETSIstandards",whichisavailablefromtheETSISecretariat.LatestupdatesareavailableontheETSIWebserver(http://www.etsi.org/ipr).PursuanttotheETSIIPRPolicy,noinvestigation,includingIPRsearches,hasbeencarriedoutbyETSI.NoguaranteecanbegivenastotheexistenceofotherIPRsnotreferencedinETSISR000314(ortheupdatesontheETSIWebserver)whichare,ormaybe,ormaybecome,essentialtothepresentdocument.ForewordThisEuropeanStandard(Telecommunicationsseries)hasbeenproducedbyETSITechnicalCommitteeServicesandProtocolsforAdvancedNetworks(SPAN).Thepresentdocumentispart1ofamulti-partdeliverablecoveringtheIntegratedServicesDigitalNetwork(ISDN);NarrowbandMulti-serviceDeliverySystem(NMDS),asidentifiedbelow:Part1:"NMDSinterfacespecification";Part2:"ProtocolImplementationConformanceStatement(PICS)proformaspecification";Part3:"TestSuiteStructureandTestPurposes(TSS&TP)specificationfortheuser";Part4:"AbstractTestSuite(ATS)andpartialProtocolImplementationeXtraInformationforTesting(PIXIT)proformaspecificationfortheuser".NationaltranspositiondatesDateofadoptionofthisEN:27October2000DateoflatestannouncementofthisEN(doa):31January2001DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):31July2001DateofwithdrawalofanyconflictingNationalStandard(dow):31July2001IntroductionThepresentdocumentspecifiestheprovisionofPublicSwitchedTelephoneNetwork(PSTN)servicesoveranexistingIntegratedServicesDigitalNetwork-BasicAccess(ISDN-BA)digitalsubscriberline(DSL).TodayPSTNterminals-normaltelephones-canbeconnectedtotheS/T-interfaceviaaTerminalAdapter(TA)withthesupportofservicesthatcanbemappedatafeasiblecostfromISDN(principallythebasiccallservices).SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)61ScopeThepresentstandarddefinesrequirementstosupporttheNarrowbandMulti-serviceDeliverySystem(NMDS)whichprovidesinterfacesconnectedviaaNetworkTerminationNode(NTN)toaLocalExchange(LE),inordertosupportexistingPSTNandISDNservicesoveranexistingISDN-BasicAccessdigitalsubscriberline(DSL).TheNarrowbandMulti-ServiceDeliverySystem(NMDS)mayalsobeconnectedviaaV5interfaceAccessNetwork(AN)toaLocalExchange(LE)inordertoprovideexistingPSTNandISDNservices.ThisoptionalarrangementisdescribedinannexDwhichidentifiestwoalternativemethodstoprovidethesameoverallfunctionality.Thepresentdocumentalsocontainsrequirementswhichrelatetothefunctionalityofa(new)NetworkTerminationNode(NTN)forsupportingbothPublicSwitchedTelephoneNetwork(PSTN)accessandIntegratedServicesDigitalNetwork-BasicAccess(ISDN-BA)S/Treferencepointinterfacesoverasingle(digitalsection)transmissionsystemasusedforexistingISDN-BA.TheNTNencompassesNT2-like(notedNT2*)functionality,physicalPSTNuserport(s)andPSTNprotocolfunctionality.AnNMDSimplementationmaycontainoneISDN-BAportand/oralimitednumberofPSTNports.TypicallyoneortwoPSTNportswouldbesupported.InordertomaintainanevolutionarypathforPSTNservices,thenationalV5PSTNprotocolmappingisassumedtoexistandformsanintegralpartofthisspecification.NOTE:Itisanunderlyingprincipleofthepresentdocumentthat,whereverpracticable,stepsmaybetakentominimizethecostoftheNTN,subjecttomaintainingtherequiredfunctionality.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,thelatestversionapplies.• Anon-specificreferencetoanETSshallalsobetakentorefertolaterversionspublishedasanENwiththesamenumber.[1]ETSIETR080(1996):"TransmissionandMultiplexing(TM);IntegratedServicesDigitalNetwork(ISDN)basicrateaccess;Digitaltransmissionsystemonmetalliclocallines".[2]ETSIETS300012-1(1996):"IntegratedServicesDigitalNetwork(ISDN);BasicUser-NetworkInterface(UNI);Part1:Layer1specification".[3]ETSIETS300324-1(1994):"VinterfacesatthedigitalLocalExchange(LE);V5.1interfaceforthesupportofAccessNetwork(AN);Part1:V5.1interfacespecification".[4]ETSIETS300347-1(1994):"VinterfacesatthedigitalLocalExchange(LE);V5.2interfaceforthesupportofAccessNetwork(AN);Part1:V5.2interfacespecification".[5]ETSIETS300402-2:"IntegratedServicesDigitalNetwork(ISDN);DigitalSubscriberSignallingSystemNo.one(DSS1)protocol;Datalinklayer;Part2:Generalprotocolspecification[ITU-TRecommendationQ.921(1993),modified]".[6]ITU-TRecommendationI.412(1988):"ISDNuser-networkinterfaces-Interfacestructuresandaccesscapabilities".SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)7[7]ETSIEN301141-2(V1.2):"IntegratedServicesDigitalNetwork(ISDN);NarrowbandMulti-serviceDeliverySystem(NMDS);Part2:ProtocolImplementationConformanceStatement(PICS)proformaspecification".[8]ITU-TRecommendationM.3603(1992):"ApplicationofmaintenanceprinciplestoISDNbasicrateaccess".[9]ITU-TRecommendationM.3602(1992):"ApplicationofmaintenanceprinciplestoISDNsubscriberinstallations".[10]ETSIETS300297(1995):"IntegratedServicesDigitalNetwork(ISDN);AccessdigitalsectionforISDNbasicaccess".3Definitionsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply:NarrowbandMulti-serviceDeliverySystem:systemthatprovidesaninterfacetothenetworkdirectlytotheLEorviaanANtosupportexistingPSTNandISDNservicesoveranISDN-BADSL.NetworkTerminationNode:functionalgroupontheusersideofthedigitalsection(NMDSinterfacenotedT*referencepoint)thatincludesfunctionalitytosupportanISDN-BAportand/oroneormorePSTNports.NetworkTerminationType2*:functionalgroupwithintheNTNwhich,attheusersideoftheT*referencepoint,performsthePSTNlayer2andtheISDNlayer2multiplexinganddemultiplexingovertheDchannel,andonlyinterprets(andthenrelays)thelayer3messagestoswitchtheBchannelstotheISDNaccessandthePSTNGatewaysasinstructedbythesignallingmessages.PSTN-Gateway:functionalgroupwithintheNTNwhichterminatesthePSTNinterfaceattheNTN.T*referencepoint:referencepointwhichprovidesaccesstotheNMDS,betweenthenetworkterminationofthedigitalsection(NT1)andtheNetworkTerminationNodefunctionalgroup.V1*referencepoint:V1referencepointwiththeadditionofPSTNfunctionalityrequiredtosupporttheNMDS.3.2AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:ANAccessNetworkBCCBearerChannelControlCPECustomerPremisesEquipmentDLCIDataLinkConnectionIdentifierDSLDigitalSubscriberLineDTMFDualToneMulti-FrequencyISDNIntegratedServicesDigitalNetworkISDN-BAIntegratedServicesDigitalNetwork-BasicAccessLELocalExchangeNMDSNarrowbandMulti-serviceDeliverySystemNTNetworkTerminationNT1NTtype1(seeETR080[1])NT2*NetworkTerminationType2*(seethedefinitioninsubclause3.1above)NTNNetworkTerminationNodeNWKNetworkLayerPSTNPublicSwitchedTelephoneNetworkPSTN-GWPSTNGatewaySAPIServiceAccessPointIdentifierTATerminalAdapterSIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)8TETerminalEquipmentTEITerminalEndpointIdentifierUNIUserNetworkInterface4GeneraldescriptionThepurposeoftheNMDSistosupportbothISDN-BAandoneormorePSTNuserportsinthesamemannersuchthattheyappeartotheuserasiftheyweredirectlyconnectedtotheLE.ThesupportofISDN-BAuserportsutilizesthesametypeoffunctionsasusedbyanNT1definedinETR080[1],whilstPSTNuserportsaresupportedusingthesamePSTNprotocolasdefinedintheV5.1interfacestandardETS300324-1[3]withsomemodifications.TheLEisserviceresponsibleforandcontrolsthetones(voicemessagesetc.)sentandreceivedovertheNMDS.Seefigure1forthefunctionalarchitectureofNMDS.PSTNUserPortUNIISDN-BADSLNTNCallControlLEISDNUserPortnationalPSTNprotocolISDNlayer2mngmntFigure1:GeneralNMDSfunctionaldiagramTheNarrowbandMulti-serviceDeliverySystem(NMDS)isdefinedattheT*referencepointandthecomplementaryV1*referencepointasshowninfigure2.OnanyNMDS,theLEmaysupportupto10PSTN(analogue)linesandtheNTNmayprovideupto10PSTN(analogue)accessports.TheprovisionofPSTNandISDNaccessportsintheLErequiresabilateralagreementbetweentheuserandtheserviceprovideratsubscriptiontime.5Layer1functions• StructureThegeneralaccessstructureisdescribedinITU-TRecommendationI.412[6].TheaccessstructureforISDN-BAinITU-TRecommendationI.412[6]isvalidalsoforthePSTNapplication.Thelayer1transportingthefullNMDSfunctionalityfromtheNTNtotheLEshallbeanISDN-BAlayer1.• ISDN-BADigitalSectionInordertopermittransparentoperationviaanAN,thereshallbenochangestotheISDN-BAdigitalsectionlayer1protocols.• ISDN-BAUNILayer1attheISDN-BAUNIshallbeinaccordancewithETS300012-1[2].• ActivationProcedures-NTNTheNTNshallpermitlayer1activationfromtheISDNUNIandlayer1activation/deactivationfromthenetwork.InordertokeeptheNTNsimple,thePSTNgatewayshallnotrequire"userside"activationprocedures.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)9TheNTNshallalsoallowthedigitalsectiontobeactivatedregardlessoftheelectricalconditionsprevailingattheISDNUNIandPSTNport.Oncethelayer1isactivatedtheNTNshallalwaystransmittheACTbitsetto1towardsthenetwork.ThisistopreventthepossibilityoftheLE/ANdeactivatingthedigitalsectionaspartoftherecoveryactionsresultingfromanISDNUNIerror.(DetailsoftheACTbitcanbefoundinETR080[1]annexAfigureA.3andsubclauseA.8.3.2.2.Itspurposeistoindicatereadinessforlayer2.)• LE/ANThenetworkshallmaintainthedigitalsectioninapermanentlyactivatedstatewheneverthePSTNprotocolsaretobesupported.Thepermanentactivationofthedigitalsectionmayinterferewithcertainmaintenanceoperationsnormallyprovidedovertheembeddedoperationschannel.TheLEshallbeabletodetecttheactivationstateoftheISDNUNIwhichwouldhaveprevailedifthePSTNportshadnotbeenpresent,usingamessage-basedmaintenancemechanismatlayer3(seesubclause7.3.1.2).• DiagnosticsTheNTNshallsupportfullISDNlayer1diagnosticloopcapability.NT2*LTPSTN-GWZNTNETV*ISDNbasicaccessdigitalsection1LEorANETS300297[10]Rec.M.3603[8]S/TAccessconnectionelementRec.M.3602[9]Customerequipment2B+D(2B1Q/4B3T)ISDNbasicaccesstransmissionsystemNT1T*ETS300012-1[2]NOTE:Thefunctionalityandlayoutshowninfigure2canonlybeoneparticularexampleandisnotrepresentativeofallarchitectureswhereNMDScanbeapplied.InactualimplementationstheNT1functionalgroupislikelytobephysicallyintegratedinanequipmentrealizingtheNTNfunctionality.Figure2:AnexampleofanNMDSscenarioforNMDS5.1PoweringAspects5.1.1PoweravailablefromthetransmissionsystemThepoweravailableforNMDSsupportistheactualpowerbudgetprovidedbytheexistingISDN-BAdigitalsection.AdditionalpowerisexpectedtobeprovidedlocallytotheNTN.WhatmayhappenunderlocalpowerfailconditionswithrespecttoNTNuserportsisdescribedbelow.HencetherearenodeviationsfromtherequirementsspecifiedintheISDN-BAstandardsinordertosupportNMDS.5.1.2NMDSbehaviourunderpowerfailconditionsTheISDN-BAUNIstandard(ETS300012-1[2])describesapotentialrequirementthatadesignatedinstrumentmaybemadeavailableonanS/TInterface.Ifthisdesignatedinstrumentisavailable,thenitshallbecapableof(atleast)makingemergencytelephonecalls.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)10ForthePSTN,thesituationisnotmandatedonaEuropeanwidebasisanddependsuponnationallyagreedregulationswhichareoutsidethescopeofthepresentdocument.TheNMDSmaybecomprisedofoneormorePSTNports,potentiallyaswellasanISDN-BAport.Henceitisnotpossibletodefineinastandardmandatorybehaviourunderpower-failconditions.Whatismorerelevantisthatmanufacturersareabletoadequatelydefinetheirsystem'sbehaviourunderpowerfailureconditions.Forthisreason,aclausehasbeeninsertedintotheProtocolImplementationConformanceStatement(PICS)document,EN301141-2[7],wheresuchbehaviourmaybeexplained.6Layer2functions6.1OverviewThelayer2usedwithintheNMDSsystem,usedforbothPSTNandISDN-BAservices,shallbeinaccordancewithETS300402-2[5]butwiththefollowingrestrictions.TheLElayer2statemachineshallbeasperETS300402-2[5].ThePSTNgatewaylayer2statemachineshallbeasdefinedinsubclause6.2ofthepresentdocument,providingarestrictedfunctionalityversionofthestatemachineinETS300402-2[5].ThePSTNgatewayshalluseasinglepermanentlyactivateddatalinkwithafixedDataLinkConnectionIdentifier(DLCI)forallcommunicationwiththenetwork.TheDLCIshallconsistofaPSTNTerminalEndpointIdentifier(TEI)allocatedfromtheautomaticTEIvalues(i.e.64-126)andServiceAccessPointIdentifier(SAPI)setequalto0.TEIvalues117to126shallbereservedforPSTNusewhenNMDSisimplementedonanaccess.ThefirstPSTNgatewaytobefittedshalluseTEI126andbeidentifiedasLine1.TEIvalues117to125arereservedforfurtherPSTNgateways,lines2to10,asshowninthetable1.Table1:AllocationofTEItoPSTNportsTEIvalueLinenumber12611252124312341225121612071198118911710ThePSTNgatewayshallnotsupportthebroadcastdatalink,orTEImanagementprocedures,andshallnotinitiatelayer2establishment,i.e.theDL_ESTABLISH_REQUESTprimitiveintheTEIassignedstateshallnotbesupported.OntheISDNport,point-to-point(i.e.TEI0)orpoint-to-multipointproceduresmaybesupportedusingthefullISDNTEIassignmentproceduresascurrentlydefined.TheseincludeTEIassignmentandremovalprocedures.However,somepreviouslyavailablevaluesarenowreserved(seetable1).ItisexpectedthatsomeimplementationsmayprovideadditionalPSTN-GWseitherasseparateequipmentconnectedtotheS/TInterfaceorasfurtherintegratedentities.IneachcasetheTEIallocationsshallcomplywiththoseshownintable1.TheTEIassociatedwitheachexternalPSTN-GWshallbepreprovisioned.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)116.2PSTN-GWlayer2statemachinemodificationsThemodificationsrequiredtotheBAlayer2statemachineforthePSTN-GWarespecifiedbelowasalistofdifferencestothestatemachinecontainedinannexDofETS300402-2[5].Deletestates1,2,3,5.0,5.2and6.Deletethefollowinginputevents:-DL-ESTABLISH-REQUEST;-DL-RELEASE-REQUEST;-DL-UNITDATA-REQUEST;-UIFRAMEINQUEUE;-MDL-ASSIGN-REQUEST;-MDL-REMOVE-REQUEST;-MDL-ERROR-RESPONSE;-T203TIME-OUT.Renumberstate4,andallreferencestoit,tostate9;renamethestateto"LINKNOTESTABLISHED".Deleteallinstancesofthefollowingoutputeventsreplacingtheeventwith"-"ifitwastheonlyactionassociatedwiththeinputevent/statecombinationunderconsideration:-DISCUIQUEUE;-STARTT203;-STOPT203;-RESTARTT203;-MDL-ERR-IND(allvariants);-DL-UNIT-DATA-IND.Replaceallinstancesof"DISCIandUIQUEUES"with"DISCIQUEUE".Forinputevent"T200TIME-OUT"instates7.0throughtostate7.3deletethe"either"option.Forinputevent"T200TIME-OUT;RC
ETSIETSIEN301141-1V2.1.1(2000-11)127Layer3functionsandmessagedefinitions7.1GeneralThePSTNnetworklayer(NWK)protocolshallbeinaccordancewithETS300324-1[3]clause13subjecttothefollowingmodificationsandrestrictions.• TheNTNshallbeconsideredasimplementingtheANpartsthroughoutETS300324-1[3]clause13.• ThePSTNcallcontrolproceduresofETS300324-1[3]shallbeused.However,thePSTNPortblockingandthePSTNRestartproceduresdefinedinETS300324-1[3]donotapplytotheNMDS.HencethefollowingeventsdescribedinETS300324-1[3]PSTNfunctionalstatemachines(clause13)arenotapplicable:MDU-CRTL(portblocked),MDU-CTRL(portunblocked),MDU-CTL(restartrequest)MDU-CTRL(restartcomplete).ItresultsthatthestatesAN0,AN6,LE0andLE6definedinETS300324-1[3](subclauses13.2.1.1and13.2.1.2)fortheV5.1interfacearenotusedbytheNMDSstatemachine.• ThemeaninganddefinitionoftheL3addrfield(ETS300324-1[3]subclause13.4.3)ismodifiedtosupporttheB-channelselectionfunctionasdescribedinclause8ofthepresentdocument.• ThepresentdocumentprovidesadditionstothemessageformatsandprocedurestothosefoundinETS300324-1[3].Thesearedocumentedinsubclause7.3.Theydefineanddescribenewmaintenancestatusenquiryprocedures.• Theprotocoldiscriminatorvaluefortheadditionalmessagesdefinedinthepresentdocument(i.e.MAINTENANCESTATUSandMAINTENANCESTATUSENQUIRY)shallbethesameasforETS300324-1[3],i.e.48H.TheNTNshallsupportthenationalPSTNrequirementsforallapplicablesignals(includingcollisions).AlltonesandannouncementsgeneratedbythenetworkshallbepassedasinbandsignallingtransparentlyovertheB-channeltothecustomer.IntheeventofnoB-channelbeingavailablethentheproceedindicationshallnotbegiventothecustomeruntilachannelbecomesavailablei.e.theproceedindicationshallnotbegeneratedbythePSTN-GW.DTMFdialleddigitsshallbepassedtransparentlyovertheB-channeltothenetwork.ThenationalPSTNmappingsarebeyondthescopeofthepresentdocument.7.2ErrorhandlingTheLEshallsupportthefullerrorhandlingproceduresdefinedinETS300324-1[3]clause13,relatingtotheV5.1PSTNprotocolwithadditionalrequirementsasindicatedinthepresentdocument.TheNTNshallsupportthefullerrorhandlingproceduresasdefinedinETS300324-1[3]clause13fortheAN,relatingtotheV5.1PSTNprotocolwithadditionalrequirementsasindicatedinthepresentdocument.Inaddition,incaseofaPSTNlayer2failure,ifaPSTNcallisestablished,thiscallisreleasedbytheLE.Uponsuccessfulre-establishmentofthePSTNlayer2,theLEshallsendaDISCONNECTCOMPLETEmessagetotheNTNandgointothe"Nullstate(LE1)"inordertoensuresynchronizationoftheNTNPSTNGWandtheLEstatemachines.NOTE:Callreleasemaycauseanetworkclearingmessagewithacause#27,destinationoutoforder,or#41,temporaryfailure,andthelocationfieldsetto'publicnetworkservingtheremoteuser',tobesenttowardstheexchangeservingtheremoteuser.7.3MaintenancefunctionsThisclausedefinesthemechanismfortheLEtobeabletodetermineifcustomerequipmentisconnectedtothePSTN-GWandtodeterminethesynchronizationstatusoftheS/Tinterface.Thesupportofthe(ISDNandPSTN)maintenancemechanismsbytheLEandNTNisoptional.ItshallusetheLayer3STATUSandSTATUSENQUIRYmessagesasdefinedinETS300324-1[3]subclause13.4,exceptthattheStateandCauseinformationelementsalreadydefinedfortheSTATUSarechangedtooptionalandonlyoneofthenewvariablelengthinformationelementsdefinedbelowshallbeincludedinaSTATUSmessage.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)137.3.1ThenewSTATUSENQUIRYandSTATUSmessagesThenewSTATUSENQUIRYandSTATUSmessagesandtheirassociatedproceduresshallfollowthosedefinedinETS300324-1[3],withthefollowingadditions:• theStateandCauseinformationelementsshallnotbeincludedintheSTATUSmessage;• newinformationelementsaredefinedfortheSTATUSandSTATUSENQUIRYmessages.ThenewmessagesshallhereafterinthepresentdocumentbereferredtoasMAINTENANCESTATUSandMAINTENANCESTATUSENQUIRYmessagestodifferentiatethemfromthoseusedaspartofthestandardPSTNProtocolprocedures.7.3.1.1PSTNmaintenancemessagesTheMAINTENANCESTATUSENQUIRYandMAINTENANCESTATUSmessagesforthePSTN-GWstatusshallbesentusingtheTEIwhichisallocatedtothatgateway(seetable1).7.3.1.1.1TheMAINTENANCESTATUSENQUIRYmessageforPSTNmaintenanceTable2:ThePSTNgatewayMAINTENANCESTATUSENQUIRYmessageBit87654321ProtocolDiscriminatorLayer3Address(note)1Layer3Address(lower)(note)MessageType11010000PSTNgatewaystatusrequestinformationelementidentifierNOTE:Thelayer3addressshallbecodedas"Layer3addressnotrelevantincurrentmessage"accordingtosubclause8.2.7.3.1.1.2TheMAINTENANCESTATUSmessageforPSTNmaintenanceThismessageshallbesentonreceiptofaMAINTENANCESTATUSENQUIRYmessagefromtheLE.TheMAINTENANCESTATUSmessagecarriesanewvariablelengthoptionalinformationelementinthedirectionNTN-LE.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)14Table3:ThePSTNgatewayMAINTENANCESTATUSmessageBit87654321ProtocolDiscriminatorLayer3Address1Layer3Address(Lower)MessageType00011110PSTNgatewaystatusresponseinformationelementidentifier00000001Informationelementlength1ext.STGWNOTE1:Thelayer3Addressshallbecodedas"Layer3addressnotrelevantincurrentmessage"accordingtosubclause8.2.STGWdefinesthestatusoftheaddressedPSTN-GW(CPEpresenceindicator).ThecodingoftheSTGWfieldshallbeaccordingtotable4.Table4:CodingoftheSTGWfieldBitsMeaning76543210000000NoCPEpresent0000001CPEconnected0000010TestUnavailableNOTE:Allothervaluesarereserved.NOTE2:ThemethodfordetectingthatCPEisconnectedisnotspecifiedhereandwilldependuponthePSTNarchitectureused.7.3.1.2ISDNmaintenancemessagesTheMAINTENANCESTATUSENQUIRYandMAINTENANCESTATUSmessagesfortheISDNUNIstatusshallbesentusingTEI126.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)157.3.1.2.1TheMAINTENANCESTATUSENQUIRYmessageforISDNmaintenanceTable5:TheMAINTENANCEISDNUNISTATUSENQUIRYmessageBit87654321ProtocolDiscriminatorLayer3Address(note)1Layer3Address(lower)(note)MessageType11010001ISDNUNIstatusrequestinformationelementidentifierNOTE:Thelayer3Addressshallbecodedas"Layer3addressnotrelevantincurrentmessage"accordingtosubclause8.2.7.3.1.2.2TheMAINTENANCESTATUSmessageforISDNmaintenanceThismessageshallbesentinresponsetothereceiptofaMAINTENANCESTATUSENQUIRYmessagefromthenetworkcontainingtheISDNUNIstatusenquiryinformationelement.TheMAINTENANCESTATUSmessagecarriesanewvariablelengthinformationelementinthedirectionNTN-LE.Table6:TheMAINTENANCEISDNUNISTATUSmessageBit87654321ProtocolDiscriminatorLayer3Address(note)1Layer3Address(Lower)(note)MessageType00011111ISDNUNIstatusresponseinformationelementidentifier00000001Informationelementlength1ext.STUNINOTE:Thelayer3addressshallbecodedas"Layer3addressnotrelevantincurrentmessage"accordingtosubclause8.2.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)16STUNIdefineswhethertheS/TInterfaceofanyparticularISDN-BAisactive(i.e.INFO3hasbeenreceived).ThecodingoftheSTUNIfieldshallbeaccordingtotable7.Table7:CodingoftheSTUNIfieldBitsMeaning76543210000000NoS/TInterfacesynchronizationonISDN-BAuserport0000001S/TInterfacesynchronizationonISDN-BAuserport0000010TestUnavailableNOTE:Allothervaluesarereserved.7.3.2Maintenancestatusprocedure7.3.2.1NormaloperationTheMaintenancestatusenquiryprocedureshallonlybeinitiatedbytheLE.ThisprocedureapplieswhentheLEwantstocheckthemaintenancestatusofagivenuserport(e.g.aPSTNgatewayoranISDNUNI)intheNTN.NostatechangeshalloccurintheLEandNTNuponperformingthemaintenancestatusenquiryprocedure.OnreceiptofaMDU-maintenance_request,theLEshallsendaMAINTENANCESTATUSENQUIRYmessageandstarttimerTm.TheLayer3addressoftheMAINTENANCESTATUSENQUIRYmessageshallbesetto7FFFh.TheMAINTENANCESTATUSENQUIRYmessageshallbecodedeitherasinsubclause7.3.1.1.1wheretheLEwantstocheckthemaintenancestatusofaPSTNgateway,orasinsubclause7.3.1.2.1wheretheLEwantstocheckthemaintenancestatusofanISDNUNI.UponreceiptofaMAINTENANCESTATUSENQUIRYmessagefromtheLE,theNTNshallrespondtotheLEwiththeappropriateMAINTENANCESTATUSmessagewiththeL3Addr=7FFFh.TheMAINTENANCESTATUSmessageshallbecodedeitherasinsubclause7.3.1.1.2wheretheMAINTENANCESTATUSENQUIRYcontainedaPSTNgatewaystatusrequestIE,orasinsubclause7.3.1.2.2wheretheMAINTENANCESTATUSENQUIRYcontainedanISDNUNIstatusrequestIE.TheLEhavingreceivedtheMAINTENANCESTATUSmessageshallstoptimerTmandshallreporttheresultinternallyusingtheMDU-maintenance_response,andremaininthesamestate.IftimerTmexpires:• thefirsttime,theMAINTENANCESTATUSENQUIRYmessageshallbere-sent,andtimerTmshallberestarted;• thesecondtimeaninternalerrorindicationshallbegeneratedandnostatechangeshalloccur.7.3.2.2ExceptionalproceduresThisclausedescribestheexceptionalproceduresinrelationtothemessagecontentwiththeexceptionoftheL3addrIE.TheL3addrIEisusedwithintheB-channelselectionprocedureasdescribedinclause8.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)177.3.2.2.1NTNInrelationtotheSTATUSENQUIRYmessagetheNTNshallimplementtheANexceptionproceduresdefinedinETS300324-1[3]withtheexceptionthatthemessagecontentvalidationshallbeextendedtosupportMAINTENANCESTATUSENQUIRYmessages,i.e.ETS300324-1[3]table10isextendedasshownintable8.MessageType:STATUSENQUIRYDirection:LEtoANTable8:STATUSENQUIRYmessagecontentInformationelementReferenceDirectionTypeLengthProtocoldiscriminator[3]13.4.2LEtoANM1L3addr[3]13.4.3LEtoANM2Messagetype[3]13.4.4LEtoANM1ISDNUNIstatusrequest7.3.1.2.1LEtoANC1PSTNgatewaystatusrequest7.3.1.1.1LEtoANC1NOTE:InthecaseofMAINTENANCESTATUSENQUIRYmessages,oneandonlyoneconditionalinformationelementshallbecontainedinthemessageandshallbehandledasmandatoryinformationelement.7.3.2.2.2LEInrelationtotheSTATUSmessagetheLEshallimplementtheLEexceptionproceduresdefinedinETS300324-1[3]withtheexceptionthatthemessagecontentvalidationshallbeextendedtosupportMAINTENANCESTATUSmessages,i.e.ETS300324-1[3]table9isextendedasshownintable9below.MessageType:STATUSDirection:ANtoLETable9:STATUSmessagecontentInformationelementReferenceDirectionTypeLengthProtocoldiscriminator[3]13.4.2ANtoLEM1L3addr[3]13.4.3ANtoLEM2Messagetype[3]13.4.4ANtoLEM1State[3]13.4.6.3ANtoLEC11Cause[3]13.4.7.9ANtoLEC13to5ISDNUNIstatusresponse7.3.1.2.2LEtoANC21PSTNgatewaystatusresponse7.3.1.1.2LEtoANC31NOTE:OnesetofconditionalelementsC1,C2orC3shallbecontainedinthemessageandshallbehandledasmandatoryinformationelement(s).InthecaseofMAINTENANCESTATUSmessagesthesetshallbeC2orC3.7.3.2.3TimerTmdefinitionTheadditionaltimerTm(seetable10below)isapplicableintheLEfortheMaintenancestatusenquiryprocedure.Table10:TimerTmbehaviourTimernumberTimeoutvalueStateCauseforstartNormalstopAtthefirstexpiryAtthesecondexpiryCrossreferenceTm10sAnyMaintenanceSTATUSENQUIRYsentReceivingofSTATUSfromANindicatingresponsetomaintenanceSTATUSENQUIRYRepeatMaintenanceSTATUSENQUIRYandrestartoftimerTmMDU-error_indication7.3.2.1SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)188B-channelselectionprocedure8.1IntroductionTheB-channelsoftheaccessareacommonresourceforboththeISDN-BAandthePSTNports.TohandletheselectionofB-channelforthePSTNportuse,anewmechanismhasbeendefined(seesubclause8.2).TheoperationoftheB-channelselectionproceduresisshowninexampleswithinannexA.8.2B-channelselectionThisclausedescribesthemechanismbywhichtheLEindicatestowhichbearerchanneltheselectedPSTN-GWshallconnectforanyparticularcall.ThisisadeparturefromtheV5.1recommendationETS300324-1[3]andcanonlyfunctionbecausetheNMDSallowsonlyonePSTNlayer3perlayertwo(addressedviaTEIs).Thelayer3address(L3addr)fieldintheV5PSTNProtocolmessagesshallbeusedtoindicatethebearerchannelasintable11.Table11:B-channelselectionviaL3addrL3ADDRB-channelL3addr=0noB-channelselectedorthattheNTNshallreleasetheB-channelL3addr=1B1selectedL3addr=2B2selectedL3addr=nBnSelected(thegeneralcase)(note)L3addr=7FFFhLayer3addressnotrelevantincurrentmessage(e.g.usedinMAINTENANCESTATUSandMAINTENANCESTATUSENQUIRYmessages)Allothervaluesarereserved.NOTE:Ingeneralthisapplies,althoughforNMDSthereareonlytwoB-channelsavailable.8.2.1LEFunctionality8.2.1.1GeneralRequirementsTheLEshallberesponsiblefortheB-channelselectionandshallnotchangedirectlybetweenthetwoB-channelsduringaPSTNcall.TheselectedB-channelshallbeindicatedintheL3addrfieldofallcallrelatedmessagessentbetweenLEandNTN.TheLEshallusetheL3addrvalue7FFFhwhensendingMAINTENANCESTATUSENQUIRYmessagesdescribedinsubclause7.3.8.2.1.1.1HandlingofvalidL3addrvaluesUponreceiptofaPSTNProtocolmessagewithavalidL3addr(seetable11)theLEshallperformoneofthefollowingactionsdependentonthemessageandL3addrvalue.a)IftheLEreceivesanESTABLISHmessagewithaL3addrthatisnot0itshallignoreanddiscardthemessage.NOTE:TheLEmaygenerateaninternalerrorindication.b)IftheLEreceivesanESTABLISHmessagewithL3addrof0itshallbeacceptedandhandledinaccordancewithclause8.2.1.2.c)IftheLEreceivesamessage(otherthanESTABLISH)withaL3addrof0,1,or2itshallcomparetheL3addrvaluewiththatexpected(i.e.thecurrentallocatedvalueforthecalltakingintoaccountthepossibilityofmessagecrossovers).IfthereceivedvalueisnotasexpectedthentheLEshallclearthecallusingthenormalcallclearingprocedures,ensuringanyconnectedB-channelisreleased.Ifthereceivedvalueisasexpected(againmakingallowanceforcrossovers)thenthemessageshallbehandledinaccordancewithclause8.2.1.2.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)19d)IftheLEreceivesamessage(otherthanESTABLISH)withaL3addrof7FFFhthentheLEshallperformeither(i)or(ii)below:i.TreatthevalueoftheL3addrasvalid,makenochangesinrelationtoitsB-channelallocationatthispoint,andcontinuewiththeprocessingofthemessageinthenormalmannerthroughthePSTNprotocolandbeyond(e.g.tocallcontrolormaintenancefunctions).ThisprocessingmayresultinthereleaseoftheB-channel(e.g.iftheLEreceivesaDISCONNECTorDISCONNECTCOMPLETEmessagewithL3addr=7FFFh).IfthemessageisnotamaintenancemessagetheLEshallclearthecallusingthenormalcallclearingprocedures,ensuringanyconnectedB-channelisreleased.OtherwisetheLEshallmakenochangesinrelationtoitsB-channelallocation.8.2.1.1.2HandlingofinvalidL3addrvaluesIftheLEreceivesamessagewithareservedvalueofL3addrthentheLEshallperformoneofthefollowingoptions:a.ignorethemessageandgenerateaninternalerrorindication;b.treattheL3addrvalueasunexpectedandclearthecallusingthenormalcallclearingprocedures,ensuringanyconnectedB-channelisreleased.8.2.1.2SpecificRequirementsforPSTNCallsTheLEshallperformthegeneralrequirementsofclause8.2.1.1beforegoingontothespecificrequirementsdescribedinthisclause.OnreceiptofanESTABLISHmessagefromtheNTN,theLEshallperformeitheroption(a)oroption(b)below:a)selecttheB-channeltobeusedandindicateitusingtheL3addrwhenreturningtheESTABLISHACKNOWLEDGEmessagetotheNTN.b)selecttheB-channeltobeusedandindicateitusingtheL3addrwhenreturningtheESTABLISHACKNOWLEDGEmessagetotheNTN,oralternativelyifselectionisnotcurrentlypossibleindicatenoB-channelselectedintheL3addrwhenreturningtheESTABLISHACKNOWLEDGEmessagetotheNTN.TheB-channelshallbereleasedbytheLEwhenreceivingtheDISCONNECTCOMPLETEmessagefromtheNTNorwhentheLEsendstheDISCONNECTmessageortheDISCONNECTCOMPLETEmessage(L3addrshallbesetto0bytheLE).PriortosendinganESTABLISHmessagetotheNTNtheLEshalldeterminetheB-channeltobeusedandindicatethisintheL3addrfieldoftheESTABLISHmessage.Forallothermessages,eitheronreceiptorpriortobeingsent,thepointsofselectionandreleaseofB-channelsbytheLEduringacallshallbeinaccordancewithNationalorOperatorrequirementssubjecttotherequirementsofthisstandard.ExamplesaregiveninAnnexA.8.2.2NTNFunctionality8.2.2.1GeneralrequirementsUponreceivinganymessagewithaTEIidentifyingaPSTNport,wheretheL3addrinthemessageisvalid(i.e.isnotareservedvalueandisnotequalto7FFFh),theNTNshallchangetheconnectiontomatchtheL3addrinthemessage.Theonlyexceptiontothisiswherethereceivedmessage(e.g.DISCONNECTorDISCONNECTCOMPLETE)resultsintheNTNenteringtheidlestatewhereuponitshallreleasetheB-channelindependentoftheL3addrinthereceivedmessage.TheNTNshallnotregardchangingbetweenB-channelsasaninvalidrequest.IftheNTNreceivesamessagewithareservedvalueofL3addrthenitshallaccordingtotheL3addrhandlingprocedures(ETS300324-1[3]subclause13.5.2.2)ignorethemessage,generateaninternalerrorindicationandsendaSTATUSmessagetotheLEwiththeL3addrreceived,theStateinformationelementindicatingthecurrentstateandtheCauseinformationelementindicatingcause"L3addresserror".SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)20IftheNTNreceivesamessagewithaL3addrof7FFFhthentheNTNshalltreatthevalueoftheL3addrasvalid,makenochangesinrelationtoitsB-channelallocationatthispoint,andcontinuewiththeprocessingofthemessageinthenormalmannerthroughthePSTNprotocolandbeyond(e.g.tocallcontrolormaintenancefunctions).ThisprocessingmayresultinthereleaseoftheB-channel(e.g.iftheNTNreceivesaDISCONNECTorDISCONNECTCOMPLETEmessagewithL3addr=7FFFh).WhensendingamessagetotheLEtheNTNshallsetthevalueoftheL3addrdependingonthemessagetype.ForMAINTENANCESTATUSmessagestheL3addrshallbesetto7FFFh.ForcallcontrolrelatedmessagestheL3addrshallbesettoindicatethecurrentlyallocatedB-channel,or0whennoB-channelisallocated.(ForexampletheL3addrshallalwaysbe0whensendinganESTABLISHmessageoraDISCONNECTCOMPLETEmessage.ExamplesofvalidactionsoftheNTNareshownintable12.Table12:NTNB-channelconnectionCurrentConnectionReceivedL3addrNewConnectionPort1,B-channel10Port1,NochannelPort2,B-channel21Port2,B-channel1Port1,Nochannel2Port1,B-channel28.2.2.2SpecificRequirementsforPSTNCallsAnESTABLISHmessagesentbytheNTNcannotcontainaB-channelallocation,sincenoallocationhasbeenmadebytheLEatthispointintime.Inthiscase,thevalueL3addr=0shallbesenttoindicatethisfact.IftheNTNreceivesanESTABLISHmessageoranESTABLISHACKmessagewhichcontainsthevalueL3addr=0thentheNTNshallfollowtherequirementsoftheNationalPSTNProtocolassociatedwithreceiptofthemessagebutshallnotconnectaB-channel.Atalatertimeamessagemaybesentwithanon-zeroL3addr,inwhichcasetheB-channelreferredtoshallbeselected.SIST EN 301 141-1 V2.1.1:2005
ETSIETSIEN301141-1V2.1.1(2000-11)21AnnexA(informative):B-channelselectionA.1GeneralThisannexprovidesexamplesofhowtheB-channelselectionprocedurefortheNMDSapplicationmaybeappliedwithinaNationalPSTNProtocol.A.2Outgoingcalls(NTNtoLE)AnoffhookgeneratedbytheusershallcausetheL3addrtobesetto"noB-channelselected"intheESTABLISHmessagesenttotheLE.B-channelselectionintheLEshallbeperformedandtheselectedB-channelreturnedintheL3addrfieldintheESTABLISHACKmessagetoNTN(seefigureA.1).TheselectedB-channelshallbeshownintheL3addrofallsignallinguntilthecalliscleared.ESTABLISHESTABLISHACKestablishindicationestablishacknowledgeoffhookL3addr=0(noB-channelselected)L3addr=1ifB-channelB1wasselected,otherwise=2forB2.NTNLEcallcontrolTerminalPSTNLE4LE3LE1AN1AN5AN2FigureA.1:Outgoi
...