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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 7: ISDN BASICS 142

7.4 Switched 56

Switched56isatransitiontechnology,whichisoftenavailableinareasoftheUSA&Canada

whereISDNisnotavailable.Asthenamesuggests,thisisaservicethatpermitsasinglebi‐

directionaldigitaldatastreamtobesentata56kbpsrate.Itcanuseeitheroneortwocop

per

pairs(“2wire”and“4wire”,respectively),dependingupontheparticularCentralOffice

configuration.Besuretodetermineinadvancewhichservicewillbeprovided.

OfcoursetwoSwitched56circuitscanbeordered,iftransmissionofstereoisdesired.

Inmostareas,switched56andISDNare“inter‐worked”withintheCentralOfficeswitches,so

thatsubscribersofbothservicescanco

nnecttoeachother(ata56kbpsrate,ofcourse).

TheXstreamcanbeusedwithSwitched56andothersynchronousdataservicesthroughthe

optionalV.35/X.21interfaceandexternalCSU/DSU(s).Wecovermoreaboutusingthe

V.35/X.21interfacetointe

rfacetoSwitched56CSU/DSUsinSection9(TheV.35/X.21Interface).

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