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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 7: ISDN BASICS 138

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DEEP TECH NOTE!

The 56kbps limitation arises from a quirk of the older telephone infrastructure. The channel

banks that have been widely employed in the long-distance network have a native 64kbps

capability, but “rob” the low order PCM bit on every sixth frame in order to convey

supervision information (on-hook/off-hook and dial pulses). On voice calls the results is

merely a slightly increased noise floor. Therefore, data applications must not use the low

order bit, leaving a 56 kbps channel rate.

As new telephone plant is built for clear 64kbps transmission and a technology called

“Signaling System 7” is deployed to allow the various elements of the phone network to

communicate without using the robbed bits, this limitation has all but disappeared.

The European network has universal full 64kbps capability.

7.3 How to Order ISDN

SeeAppendix8(orderingISDN:ETS‐300)andAppendix10(orderingISDNfortheUSA&Canada)

foradditionalinformationandISDNorderformstosendtoyourTelco.

Dealing with the Phone Company

Asisoftenthecasewhenwebroadcastersinterfacewiththephonepeople,thelinesof

communicationonISDNcangetali

ttletangled.Faceit:wearenottheusualcustomers.The

goodnewsisthatorderingISDNisprettyroutinethesedays,andproblemsarereallyquiterare.

Thefollowinginformationisintendedtohelpifyourunintodifficulties.

Thefirstorderofbusinessistofindsomeonewhokn

owswhatISDNis.Whileyourusual

accountagentwillbethenormalentrypoint,youmightneedtotalktosomeotherphone

companypeoplebeforeyoufindonewhounderstandsyourneeds.SomeoftheregionalBell

companiesofferasinglepointofcontactnumberforswitcheddigitalservices.SomeTe

lcosuse

“Resellers”or“Agents”.Ifso,youshouldbesuretoaskwhatexperiencetheparticularagent

haswithorderinglinesforhighfidelityaudiocodecs.Ifindoubt,godirecttotheTelco.And,

alwaysorderyourlineinwritingusingtheISDNorderformsintheApp

endixofthismanual.

Thissectionisintendedtobeusedasanoverview.Itisnotnecessarytounderstandeverything

inthissectiontogetanISDNlineforaZephyrXstream.

Theeasiest(andmostaccurate)waytoorderthelineistousetheappropriateFaxableISDN

OrderFormfr

omAppendix7or8(OrderingISDN).Appendix8alsoincludesalistofcontact

telephonenumbersformanyoftheregionaltelephonecompaniesintheUSA&Canada.

Details, Details

Inordertocommunicateaccuratelywhatitisyouneed,youmightwanttolearnaboutthe

natureoftheISDNserviceandthevoca

bularyusedtodescribeit.Aswithanything,forbest

results,ithelpstoknowwhatyouaretalkingabout.Wealreadyhaveagoodstart,butthereis

moretolearn.

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