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1、Chapter2: IntroductiontoAnalogTelephony2-1Copyright?1998,CiscoSystems,Inc.ObjectivesUponcompletionofthischapter,youwillbeabletoperformthefollowingtasks:Givenananalogtelephonynetwork,identifytheroleofeachcomponentwithinthenetwork.Thecomponentsaretelephones,lines,loops,switches,andtrunks.Givenanana
2、logtelephonynetwork,describethetelephonysignalingonlinesandtrunksGivenatelephonynetwork,tracethepathofatelephonecallTelephoneCallComponents2-3Copyright?1998,CiscoSystems,Inc.TelephoneCallComponentsTelephoneLocalloopVoiceswitchCO(centraloffice)PBX(privatebranchexchange)TrunksTelephoneComponents2-5
3、Copyright?1998,CiscoSystems,Inc.Handset(receiverandtransmitter)SwitchhookHybrid(2-to-4wireconverter)SidetoneDialerRingerTelephoneComponentsTelephone CompanySwitchTelephone2-WireLocalLoopRingerSwitchHookLoopLengthComp.Dialing(PulseorTone)BalanceNetwork2-Wire4-WireHybridReceiverTransmitterTelephone
4、Signaling2-7Copyright?1998,CiscoSystems,Inc.TelephoneSignalingSupervisorysignalingReleaseconnection(on-hook)Requestforservice(off-hook)RingingAddressing(dialeddigits)PulseDTMFOn-HookTelephoneSwitchLocalLoopLocalLoop-48DCVoltage(Battery)DCOpenCircuitNoCurrentFlowHandsetoncradle andswitchhookisopen
5、LocalLoopLocalLoopOff-HookClosedCircuitDCCurrentDialToneTelephoneSwitchOff-HookRingingLocalLoopLocalLoopOff-HookClosedCircuitRing-BackToneDCCurrentRingingVoltageTelephoneSwitchRinging(cont.)UnitedStates CadenceEurope Cadence0.40.40.22Sec2Sec4SecPulseMake(CircuitClosed)Break(CircuitOpen)Off-HookDi
6、alingInterdigitNextDigitPulsePeriod50ms—20pulsespersecond 100ms—10pulsespersecondUS:60/40Break/Make700msDualToneMultifrequencyDTMF123456789*0#120913361477697770852941Timing:60msBreak40msMakeInformationalSignaling—CallProgressIndicators(UnitedStates)ToneFrequency(Hz)OnTime(sec)OffTime(sec)DialBusy
7、Ring-back,lineRing-back,PBXCongestion(toll)Reorder(local)Receiveroff-hookNosuchnumber Confirmationtone350+440480+620440+480440+480480+620480+6201400+2060+2450+2600200to400Continuous0.50.524130.20.30.30.20.10.1Continuou
