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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 7: ISDN BASICS 139

CSD and CSV

RecallthateachISDNBRIhastwopossibleBchannels.Itispossibletoorderalinewithoneor

bothoftheBchannelsenabled–andeachmaybeenabledforvoiceand/ordatause.Phone

terminologyfortheclassofserviceis“CSV”forCircuitSwitchedVoiceand“CSD”forCircuit

SwitchedData.

CSVisforcall

susingstandardvoicephoneserviceandallowsISDNtointerwork(i.e.tocall)with

analogphonelinesandphones.CSDisrequiredforZephyrconnections.Eventhoughyoumay

besendingvoice,thecodecbitstreamoutputlookslikecomputerdatatoth

ephonenetwork.

“AlternateCSD/CSV”or“Alternatevoice/data”meansbothcapabilitiesaresupported.

h

HOT TIP!

While the D channel is always present for signaling purposes, it can, in theory, be used for

packet data connections. ISDN lines where the D channel is used for signaling only are

sometimes referred to as “2B+0D” rather than “2B+D” service. D channel packet service is

not widely available.

ZephyrXstreamallowstheoptionofavoicecalloneitherofthechannelsaswellasthecoded

hi‐fiaudio.Thiscapabilityexistsonbothchannels.Thus,youcanmakecallstoanynormal

telephonenumberononechannelwhileaprogramisbeingtransmittedontheother.The

Xstreameve

nallowsyoutoplacetwoofthesevoicecalls,butthen,ofcourse,youwouldnotbe

abletotransmithi‐fidelitycodecdata,sincebothchannelswouldbeinuse.

CallsfromaZephyrXportthatisconnectedtoananalog"POTS"linealsouseCSV.

Therefore,youwillwanttoorderCSVaswellasCSDononeorbothBcha

nnels.Typically,you

wouldorderanISDNBRI2B+DlinewithalternateCSV/CSDonbothchannels.Ifyoudon’tneed

voicepossibilityonthechannels,youwant2B+DwithonlyCSDenabled.

NT1s

TheISDNstandardspecifiestworeferencepoints,th

e‘U’andthe‘S’interfaces.

TheUisthesingle‐pairbarecopperfromtheTelcoCO.Thisissometimesreferredtoasthe“2‐

wire”interface.Adevicecalleda‘NetworkTermination,Type1’(NT1orNT‐1)convertsthisto

thetwo‐pairSinterface.Th

eSinterfacesometimesiscalledthe“4‐wireinterface.TheNT1can

alsobegenericallybereferredtoasNCTE(NetworkChannelTerminationEquipment).

OutsidetheUSA&Canada,theNT1(andNCTEforothertypesoflines)isnearlyalwaysprovided

bythetelephonecompany,andthereforetheSinter

facemustbeonuserequipment.Insome

countries,itisreferredtoasaNTBA(NetworkTerminationBasicAccess).IntheUSAand

Canada,theNT1isusuallyprovidedbytheuser.Therefore,theZephyrXstreamincludesboth

interfaces.TheUinterfaceontheZephyrXstreamisona2‐pi

n6‐positionminiaturemodular

plug(RJ‐11style).TheSinterfaceisonan8‐pin8‐positionminiaturemodularplug(RJ‐45style).

RefertomanualSection3(GuidedTouroftheHardware)foradditionalinformationonZephyr

Xstream'sbuilt‐inNT1.

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