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Atelecommunication circuit is a path in atelecommunications network used totransmit information. Circuits have evolved from generally being built on physical connections between individual hardware cables, as in an analog phone switch, tovirtual circuits established overpacket switching networks.
A telecommunication circuit may be defined as follows:[citation needed]
In operational terms, a telecommunication circuit may be capable of transmitting information in only one direction (simplex circuit), or it may be bi-directional (duplex circuit). Bi-directional circuits may support half-duplex operation, when only one end of the channel transmits at any one time, or they may support full-duplex operation where independent simultaneous transmission occurs in both directions.[2]
Originally, telecommunication circuits transmittedanalog signals.Radio stations used them asstudio transmitter links (STLs) or asremote pickup unit (RPU) forsound reproduction, sometimes as a backup to other means. Later lines weredigital, used in pair-gain applications, such ascarrier systems, or in enterprisedata networks.
Aleased line,private circuit, ordedicated circuit, is a circuit that is dedicated to only one use and is typically not switched at a central office. The opposite is aswitched circuit, which can be connected to different paths in a switching center or telephone exchange.Plain old telephone service (POTS) andISDN telephone lines are switched circuits.
On certainpacket switching telecommunication circuits, avirtual circuit may be created, while sharing the physical circuit.
This article incorporatespublic domain material fromFederal Standard 1037C.General Services Administration. Archived fromthe original on 2022-01-22. (in support ofMIL-STD-188).