ETSI EN 300 357 V1.2.1 (2001-05)

Integrated Services Digital Network (ISDN); Completion of Calls to Busy Subscriber (CCBS) supplementary service; Service description

REN/SPAN-110096

Digitalno omrežje z integriranimi storitvami (ISDN) – Dopolnilna storitev: dokončanje klicanja zasedenega naročnika (CCBS) – Opis storitve

General Information

• Status: Published
• Publication Date: 27-May-2001
• Technical Committee: SPAN 11 - SPAN Services, Applications, Numbering, Naming and Addressing (SANNA)
• Current Stage: 12 - Completion
• Due Date: 01-Jun-2001
• Completion Date: 28-May-2001
• Ref Project: SIST EN 300 357 V1.2.1:2005 - Integrated Services Digital Network (ISDN); Completion of Calls to Busy Subscriber (CCBS) supplementary service; Service description

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.VWRULWHYIntegrated Services Digital Network (ISDN); Completion of Calls to Busy Subscriber (CCBS) supplementary service; Service description33.080Digitalno omrežje z integriranimi storitvami (ISDN)Integrated Services Digital Network (ISDN)ICS:Ta slovenski standard je istoveten z:EN 300 357 Version 1.2.1SIST EN 300 357 V1.2.1:2005en01-januar-2005SIST EN 300 357 V1.2.1:2005SLOVENSKI
STANDARD



SIST EN 300 357 V1.2.1:2005



ETSIEN300357V1.2.1(2001-05)EuropeanStandard(Telecommunicationsseries)IntegratedServicesDigitalNetwork(ISDN);CompletionofCallstoBusySubscriber(CCBS)supplementaryservice;ServicedescriptionSIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)2ReferenceREN/SPAN-110096KeywordsCCBS,ISDN,stage1,supplementaryserviceETSI650RoutedesLuciolesF-06921SophiaAntipolisCedex-FRANCETel.:[phone]Fax:[phone]SiretN°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:[e-mail]opartmaybereproducedexceptasauthorizedbywrittenpermission.Thecopyrightandtheforegoingrestrictionextendtoreproductioninallmedia.©EuropeanTelecommunicationsStandardsInstitute2001.Allrightsreserved.SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)3ContentsIntellectualPropertyRights.5Foreword.51Scope.62References.63Definitionsandabbreviations.73.1Definitions.73.2Abbreviations.84Description.85Procedures.85.1Provisionandwithdrawal.85.2Normalprocedures.95.2.1Registrationanderasure.95.2.2Activationanddeactivation.95.2.2.1Activation.95.2.2.2Deactivation.105.2.3Invocationandoperation.105.2.4Interrogation.115.3Exceptionalprocedures.115.3.1Registrationanderasure.115.3.2Activationanddeactivation.115.3.2.1Activation.115.3.2.2Deactivation.125.3.3Invocationandoperation.125.3.3.1ExceptionalsituationatdestinationB'sside.125.3.3.2ExceptionalsituationatuserA'sside.135.3.3.3Networkcongestion.135.3.4Interrogation.136Intercommunicationconsiderations.146.1Interworkingwithnon-ISDNs.146.2InterworkingwithprivateISDNs.147Interactionwithothersupplementaryservices.147.1Adviceofchargeservices.147.1.1Charginginformationatcallset-uptime.147.1.2Charginginformationduringthecall.147.1.3Charginginformationattheendofacall.147.2Callwaiting.157.3Callhold.157.4Explicitcalltransfer.157.5Numberidentificationservices.157.5.1Callinglineidentificationpresentation.157.5.2Callinglineidentificationrestriction.157.5.3Connectedlineidentificationpresentation.157.5.4Connectedlineidentificationrestriction.157.6Closedusergroup.157.7Completionofcallstobusysubscriber.167.8Conferenceservices.167.8.1Conferencecall,add-on.167.8.2Meet-meconference.167.9Directdiallingin.167.10Diversionservices.167.10.1Callforwardingunconditional.167.10.2Callforwardingbusy.17SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)47.10.3Callforwardingnoreply.177.10.4Calldeflection.187.11Freephone.187.12Maliciouscallidentification.187.13Multiplesubscribernumber.187.14Subaddressing.187.15Terminalportability.187.16Threeparty.187.17User-to-usersignalling.19AnnexA(normative):Determinationoftheexistenceofcompatibleterminals.20AnnexB(informative):Bibliography.21History.22SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)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).InaccordancewithITU-TRecommendationI.130[1],thefollowingthreelevelstructureisusedtodescribethesupplementarytelecommunicationsservicesasprovidedbyEuropeanpublictelecommunicationsoperatorsunderthepan-EuropeanIntegratedServicesDigitalNetwork(ISDN):-Stage1:isanoverallservicedescription,fromtheuser'sstandpoint;-Stage2:identifiesthefunctionalcapabilitiesandinformationflowsneededtosupporttheservicedescribedinstage1;and-Stage3:definesthesignallingsystemprotocolsandswitchingfunctionsneededtoimplementtheservicedescribedinstage1.Thepresentdocumentdetailsthestage1aspects(overallservicedescription)fortheCompletionofCallstoBusySubscriber(CCBS)supplementaryservice.Thestage2aspectsaredetailedinETS300358(seebibliography)andthestage3aspectsaredetailedinEN300359-1[7]andEN300356-18[8].NationaltranspositiondatesDateofadoptionofthisEN:25May2001DateoflatestannouncementofthisEN(doa):31August2001DateoflatestpublicationofnewNationalStandardorendorsementofthisEN(dop/e):28February2002DateofwithdrawalofanyconflictingNationalStandard(dow):28February2002SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)61ScopeThepresentdocumentdefinesthestageoneoftheCompletionofCallstoBusySubscriber(CCBS)supplementaryserviceforthepan-EuropeanIntegratedServicesDigitalNetwork(ISDN)asprovidedbyEuropeanpublictelecommunicationsoperators.Stageoneisanoverallservicedescriptionfromtheuser'spointofview(seeITU-TRecommendationI.130[1]),butdoesnotdealwiththedetailsofthehumaninterfaceitself.ThepresentdocumentdefinestheinterworkingrequirementsofprivateISDNswiththepublicISDN.Inaddition,thepresentdocumentspecifiesthebasefunctionalitywheretheserviceisprovidedtotheuserviaaprivateISDN.ThepresentdocumentdoesnotspecifytheadditionalrequirementswheretheserviceisprovidedtotheuserviaatelecommunicationsnetworkthatisnotanISDNbutdoesincludeinterworkingrequirementsofothernetworkswiththepublicISDN.Interactionswithsupplementaryservicesnotlistedinclause7areoutsidethescopeofthepresentdocument.Chargingprinciplesareoutsidethescopeofthepresentdocument.TheCCBSsupplementaryserviceenablesuserA,encounteringabusydestinationB,tohavethecallcompletedwithouthavingtomakeanewcallattemptwhenthedestinationBbecomesnotbusy.TheCCBSsupplementaryserviceisapplicabletoallcircuit-switchedtelecommunicationsserviceswiththefollowingexceptions:a)call2,ofthevideotelephonyteleservice(seeETS300264inbibliography);b)allothercircuit-switchedtelecommunicationsservicesrequiringtheuseofmorethanoneB-channel.ThepresentdocumentisapplicabletothestagetwoandstagethreedocumentsfortheISDNCCBSsupplementaryservice.Theterms"stagetwo"and"stagethree"arealsodefinedinITU-TRecommendationI.130[1].Wherethetextindicatesthestatusofarequirement(i.e.asstrictcommandorprohibition,asauthorizationleavingfreedom,orasacapabilityorpossibility),thisshallbereflectedinthetextoftherelevantstagetwoandstagethreedocuments.Furthermore,conformancetothepresentdocumentismetbyconformingtothestagethreedocumentwiththefieldofapplicationappropriatetotheequipmentbeingimplemented.Therefore,nomethodoftestingisprovidedforthepresentdocument.2ReferencesThefollowingdocumentscontainprovisionswhich,throughreferenceinthistext,constituteprovisionsofthepresentdocument.• Referencesareeitherspecific(identifiedbydateofpublication,editionnumber,versionnumber,etc.)ornon-specific.• Foraspecificreference,subsequentrevisionsdonotapply.• Foranon-specificreference,subsequentrevisionsdoapply.[1]ITU-TRecommendationI.130(1988):"MethodforthecharacterizationoftelecommunicationservicessupportedbyanISDNandnetworkcapabilitiesofanISDN".[2]ITU-TRecommendationI.112(1988):"VocabularyoftermsforISDNs".[3]ITU-TRecommendationI.210(1993):"PrinciplesoftelecommunicationservicessupportedbyanISDNandthemeanstodescribethem".[4]ITU-TRecommendationE.164(1997):"Theinternationalpublictelecommunicationnumberingplan".SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)7[5]ITU-TRecommendationQ.9(1988):"Vocabularyofswitchingandsignallingterms".[6]ITU-TRecommendationI.221(1993):"Commonspecificcharacteristicsofservices".[7]ETSIEN300359-1(V1.3.2):"IntegratedServicesDigitalNetwork(ISDN);CompletionofCallstoBusySubscriber(CCBS)supplementaryservice;DigitalSubscriberSignallingSystemNo.one(DSS1)protocol;Part1:Protocolspecification".[8]ETSIEN300356-18(V3.1.3):"IntegratedServicesDigitalNetwork(ISDN);SignallingSystemNo.7;ISDNUserPart(ISUP)version3fortheinternationalinterface;Part18:CompletionofCallstoBusySubscriber(CCBS)supplementaryservice[ITU-TRecommendationQ.733,clause3(1997),modified]".3Definitionsandabbreviations3.1DefinitionsForthepurposesofthepresentdocument,thefollowingtermsanddefinitionsapply:basicaccess:seeITU-TRecommendationQ.9[5],clause1,definition1551basiccallprocedures:proceduresbywhichacall(asaninstanceofatelecommunicationsservice)isestablishedandterminatedbusy:seeITU-TRecommendationI.221[6],clause3.CCBSbusy:anyoneofthefollowingconditionswillcauseuserAtobeconsideredasCCBSbusy:-maximumnumberofcallsreachedatuserA;-noB-channelsavailableatuserA;-CCBSrecallpendingonuserA.CCBScall:callgeneratedbythenetworkfromuserAtodestinationBresultingfromuserA'sacceptanceofaCCBSrecallCCBSrecall:indicationinforminguserAthatthenetworkisreadytoinitiateaCCBScalltodestinationBandthatthenetworkisawaitingaresponsetothisindicationCCBSrecalltimer:maximumtimethenetworkwillwaitforuserAtorespondtoaCCBSrecall.Thevalueofthistimershallbeaminimumof10secondsandamaximumof20secondsCCBSrequest:instanceofanactivationoftheCCBSsupplementaryservicewhichisheldinaqueuependingthecorrectconditionsfortheCCBSsupplementaryservicetobecompletedCCBSservicedurationtimer:maximumtimetheCCBSsupplementaryservicewillremainactivatedforuserAwithinthenetwork.Thevalueofthistimershallbeaminimumof15minutesandamaximumof45minutescompatibleterminal:terminalwhichcansupportthebearerserviceorteleservicerequestedfortheoriginalcalltodestinationBandwhichcanacceptcallstotheISDNnumberandsubaddressidentifyingthecalleduserintheoriginalcalltodestinationBdestinationB:entityaddressedintheoriginalcalldestinationBidleguardtimer:timethenetworkwillwaitafterdestinationBhasbecomenotbusybeforeinforminguserA.Thevalueofthistimershallbeamaximumof15secondsIntegratedServicesDigitalNetwork(ISDN):seeITU-TRecommendationI.112[2],clause2.3,definition308ISDNnumber:numberconformingtothenumberingplanandstructurespecifiedinITU-TRecommendationE.164[4]primaryrateaccess:seeITU-TRecommendationQ.9[5],clause1,definition1552SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)8retentiontimer:thistimerspecifiestheamountoftimethatthenetworkretainsalloftheinformationsuppliedbythecallinguserwhenthecallencountersbusy.Thistimerispartofthebasiccallprocedures.Althoughthistimerisoptionalforthebasiccallprocedures,itisneededfortheoperationoftheCCBSsupplementaryservice.Thevalueshallbegreaterthan15secondsservice;telecommunicationsservice:seeITU-TRecommendationI.112[2],clause2.2,definition201subaddress:seeITU-TRecommendationE.164[4],clause11.2supplementaryservice:seeITU-TRecommendationI.210[3],clause2.4suspendedCCBSrequest:CCBSrequestwhichcannotbeservedevenifdestinationBisnotbusy,becauseuserAisbusyorCCBSbusyuserA:userwhooriginatedthecallandtowhomtheCCBSsupplementaryserviceisprovided3.2AbbreviationsForthepurposesofthepresentdocument,thefollowingabbreviationsapply:CCBSCompletionofCallstoBusySubscriberISDNIntegratedServicesDigitalNetwork4DescriptionTheCCBSsupplementaryserviceenablesuserA,encounteringabusydestinationB,tohavethecallcompletedwithouthavingtomakeanewcallattemptwhenthedestinationBbecomesnotbusy.WhenuserArequeststheCCBSsupplementaryservice,thenetworkwillmonitorfordestinationBbecomingnotbusy.WhendestinationBbecomesnotbusy(i.e.accessresources,e.g.atleastoneB-channel,arenotbusy)thenthenetworkwillwaitashorttimeinordertoallowtheresourcestobere-usedfororiginatingacall.Iftheresourcesarenotre-usedbydestinationBwithinthistime,thenthenetworkwillautomaticallyrecalluserA.WhenuserAacceptstheCCBSrecall,thenthenetworkwillautomaticallygenerateaCCBScalltodestinationB.TheCCBSsupplementaryserviceshallbeavailabletouserswhoareconnectedtothenetworkviaabasicaccessoraprimaryrateaccess.NOTE:AsupplementaryserviceprovidedtodestinationBwhichpreventstheregistrationofCCBSrequestsisoutsidethescopeofthepresentdocument.5Procedures5.1ProvisionandwithdrawalTheCCBSsupplementaryserviceshallbeprovidedtouserAafterpriorarrangementwiththeserviceproviderorshallbegenerallyavailable.TheCCBSsupplementaryserviceshallbewithdrawnbytheserviceprovideruponrequestofthesubscriberorforserviceproviderreasons.Asaserviceprovideroption,theCCBSsupplementaryservicecanbeofferedwithasubscriptionoption,whichshallapplytothewholeaccessofuserA.Thesubscriptionoptionisdetailedintable1.SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)9Table1SubscriptionoptionValuesRecallmode-Global,i.e.CCBSrecallofferedtoallterminals.-Specific,i.e.CCBSrecallofferedtotheterminal,whichactivatedtheCCBSsupplementaryservice.Ifthesubscriptionoptionisnotoffered,oneofthetwovaluesshallbechosenbytheserviceprovider.5.2Normalprocedures5.2.1RegistrationanderasureNotapplicable.5.2.2Activationanddeactivation5.2.2.1ActivationWhenthenetworkencountersabusydestinationB,itshallretainthecallinformationfortheCCBSsupplementaryservicefortheperioddefinedbytheretentiontimer.DuringthistimeuserAcanactivatetheCCBSsupplementaryservice.Thevalueoftheretentiontimershallbeaminimumof15seconds.UponreceiptofarequestfortheactivationoftheCCBSsupplementaryservicethenetworkshallcheckthatacompatibleterminalexistsatdestinationB(seeannexA).WhenithasbeenestablishedthatacompatibleterminalexistsatdestinationB,thenetworkshallregistertheCCBSrequestbasedontheretainedcallinformationanduserAshallbeinformedthattheactivationwassuccessful.MultiplerequestsagainstdestinationBshallbequeued.WhentheactivationoftheCCBSsupplementaryserviceisacceptedtheCCBSservicedurationtimershallbestarted.Thevalueofthistimershallbeaminimumof15minutesandamaximumof45minutes.ThenetworkshallmonitorfordestinationBbecomingnotbusy.UserAcanhavealimitednumberofCCBSrequestsoutstanding.Thislimitshallapplyingeneralforallusersanditsvalueshallbeanetworkprovideroptionwithamaximumvalueof5.Therequestscanbetodifferentdestinations,orcanbetothesamedestinationBwithdifferentservicerequirements(e.g.bearerserviceandteleservicerequirements),orasanetworkoption,thesameservicerequirements.DestinationBcanhavealimitednumberofincomingCCBSrequestsoutstanding.Thislimitshallapplyingeneralforallusersanditsvalueshallbeadestinationnetworkoptionwithamaximumvalueof5.Asafurtherdestinationnetworkoption,thesizeofthedestinationBCCBSqueuecanbereducedforindividualusers.Thereducedsizecanhavezerolength.NOTE1:ReducingthequeuelengthallowsanetworkoperatortobalancetheinteractionbetweentheCCBSsupplementaryserviceandothersupplementaryservices(e.g.thecallwaitingsupplementaryserviceandthefreephonesupplementaryservice).NOTE2:Asaconsequenceofthequeuehavingzerolength,theCCBSsupplementaryservicewillbeunavailabletouserscallingdestinationB.HavingactivatedtheCCBSsupplementaryservice,userAcanoriginatecallsandreceivecallsasnormal.SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)105.2.2.2DeactivationUserAcansendanyofthefollowingdeactivationrequests:a)deactivatealloutstandingCCBSrequests;orb)deactivateaspecificCCBSrequest.Thisrequestshallcontainenoughinformationtocorrelatewiththeinitialactivation.Uponsuccessfuldeactivation,thecorrespondingCCBSrequestshallbediscarded.UserAshallbeinformedthatthedeactivationissuccessful.IfaspecificCCBSrequestisdeactivated,thenetworkshallindicatewhichspecificCCBSrequesthasbeendeactivated.Ifthevalueofthesubscriptionoption"recallmode"is"specific"thentheusercandeactivateonlythoseoutstandingCCBSrequestsmadefromthatterminal.Ifthevalueofthesubscriptionoption"recallmode"is"global",thenfromanyofuserA'sterminals,userAcandeactivateanyoutstandingCCBSrequeststoredforthatuser.5.2.3InvocationandoperationWhendestinationBbecomesnotbusy(e.g.acallisterminated)ordestinationBisnotbusywheneitherofthefollowingoccurs:-aCCBSrequestisreceived;or-aCCBSrequestbecomesnotsuspended,thenthedestinationBCCBSqueueshallbeprocessed,providedthatanentryinthedestinationBCCBSqueueisnotcurrentlybeingprocessed.Entriesshallnotbeprocessedinparallel.Thefirstrequest,whichisnotsuspended,shallbeselectedandthenetworkshallreserveondestinationB'sinterfacetheresources(e.g.aB-channel)whicharenecessarytocompletetheCCBScall.DestinationBcanusethereservedaccessresourcesorotherfreeresources,inordertooriginateacall.Anincomingcallshallnotusethesereservedresources.Acheckforacompatibleterminal,whichisnotbusyatdestinationB,shallbeperformed(seeannexA).Ifsuchaterminaldoesnotexist,furtherrequests,whicharenotsuspended,shallbeexamined.Whenaterminalisfound,thenetworkshallstartthedestinationBidleguardtimer.Thevalueofthistimershallbeamaximumof15seconds.NOTE:ThistimerenablesdestinationBtoinitiateacallbeforeanyCCBSrequestisprocessed.WhenthedestinationBidleguardtimerexpires,thenprovidedthatinterfaceresourcesarestillavailableatdestinationB,andacompatibleterminalatdestinationBisstillnotbusy,userAshallbeinformed.IfuserAisneitherbusynorCCBSbusy,userAshallberecalledwithanindicationthatitisaCCBSrecallandwithanindicationofwhichCCBSrequestitappliesto,andtheCCBSrecalltimershallbestarted.Thevalueofthistimershallbeaminimumof10secondsandamaximumof20seconds.IfuserAacceptstherecallbeforetheCCBSrecalltimerexpires,thenthenetworkshallinitiatetheCCBScalltodestinationB.WhenthenetworkreceivesanindicationthatthedestinationBisbeinginformedoftheCCBScall,thecorrespondingCCBSrequestshallbeconsideredascompleted.Whilsttheidleguardtimerisrunning,andalsowhilstawaitingtheCCBScalltodestinationB,anewincomingcallshallnotbeofferedtodestinationBifithasservicerequirementsanddestinationselectioninformationidenticaltothe(notsuspended)requestwhichiscurrentlybeingprocessedinthedestinationBCCBSqueue.Forsuchincomingcalls,thecalledusershallbeconsideredasbeingbusyandthecallingusershallbeinformedasforbasiccallprocedures.TheCCBSrequestsinthedestinationBCCBSqueueshallbeprocessedintheordertheyarereceived,althoughtheactualmechanismforprocessingthequeueisoutsidethescopeofthepresentdocument.DuringtheprocessingofthedestinationBCCBSqueue,CCBSrequests,whicharecurrentlysuspended,shallbeignored.SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)11If,foranyreason,noCCBScallresultsfromtheprocessingofaCCBSrequest,thenprovidedthataccessresourcesarestillavailableatdestinationB,thenextrequestinthedestinationBCCBSqueueshallbeselectedforprocessing.ThisprocedureshallberepeateduntiltheprocessingofthedestinationBCCBSqueueiscomplete.If,foranyreason,noCCBScallresultsfromtheprocessingofaCCBSrequestandtheaccessresourcesarenolongeravailableatdestinationB,thentheresourcesreservedfortheCCBSsupplementaryserviceshallbereleasedandthenetworkshallmonitorfordestinationBbecomingnotbusy.IfallofthedestinationBCCBSqueuehasbeenprocessedandnoCCBScallresults,thenprocessingiscompleteandtheresourcesreservedfortheCCBSsupplementaryserviceshallbereleased.IfrequestswhicharenotsuspendedexistinthedestinationBCCBSqueue,then:-ifdestinationBisbusy,thenetworkshallmonitorfordestinationBbecomingnotbusy;or-ifdestinationBisnotbusy,thenthedestinationBCCBSqueueshallbeprocessedwhenanothercallisterminated,oraCCBSrequestisreceived,oraCCBSrequestbecomesnotsuspended.5.2.4InterrogationUserAcanrequestthestatusoftheCCBSsupplementaryservice.Inresponsetotherequestthefollowinginformationshallbeprovided:a)inresponsetoageneralrequestuserAshallbegivenalistoftheaddressesagainstwhichCCBSrequestsareoutstanding;b)inresponsetoaspecificrequestconcerningoneparticularaddress,userAshallbeinformedwhetherornotuserAhasaCCBSrequestoutstandingagainstthataddress.NOTE:Inbothcases,thenetworkprovidesinformationrelatingtoCCBSrequestsanditisamatterforterminalimplementationwhetherornottheuserisgiveninformationaboutCCBSrequestswhicharenotcompatiblewiththeterminal.5.3Exceptionalprocedures5.3.1RegistrationanderasureNotapplicable.5.3.2Activationanddeactivation5.3.2.1ActivationTheactivationoftheCCBSsupplementaryserviceshallberejectediftheCCBSsupplementaryserviceisnotprovidedtotheuser.TheactivationoftheCCBSsupplementaryserviceshallberejectedifthereisnocompatibleterminalatdestinationB.IfthenetworkcannotacceptuserA'srequesttoactivatetheCCBSsupplementaryservice,thenetworkshallinformuserAandgiveoneofthefollowingreasons:a)shorttermdenial:thenetworktemporarilycannotacceptuserA'srequesttoactivatetheCCBSsupplementaryservice.AlaterattempttoactivatetheCCBSsupplementaryserviceforthesamedestinationBmaysucceed.Thisreasonwillbegivene.g.:-ifuserAhasreachedthelimitofCCBSrequestsoutstanding;-iftherearealreadythemaximumnumberofrequestsqueuedagainstdestinationB;-ifthereisaninteractionwithasupplementaryservicewhichtemporarilypreventstheactivationoftheCCBSsupplementaryservice;-ifnocompatibleterminalisfoundatdestinationB.SIST EN 300 357 V1.2.1:2005



ETSIETSIEN300357V1.2.1(2001-05)12b)longtermdenial:thenetworkcannotacceptuserA'srequesttoactivatetheCCBSsupplementaryserviceandalaterattempttoactivatetheCCBSsupplementaryserviceforthesamedestinationBwillalsoberejected.AnexampleoflongtermdenialiswheredestinationB'snetworkdoesnotsupporttheCCBSsupplementaryservice.IfdestinationBisnolongerbusywhentheCCBSrequestarrives,thentheCCBSrequestshallbehandledatdestinationBasdescribedinclause5.2.2.1.5.3.2.2DeactivationACCBSrequestshallbeautomaticallydeactivatedbythenetworkanduserAinformedif:a)theCCBSservicedurationtimerexpires;b)userAdoesnotaccepttheCCBSrecallbeforetherecalltimerexpires;c)destinationBinvokesaservicethatconflictswiththeexistingCCBSrequestanddeactivationbecomesnecessary.TheusershallonlybegiveninformationaboutdeactivationofaCCBSrequestifthatuserwouldhavebeengiventheCCBSrecallassociatedwiththatCCBSre
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