In telecommunication, a data transmission circuit is the transmission media and the intervening equipment used for the data transfer between data terminal equipment (DTEs).
A data transmission circuit includes any required signal conversion equipment.
A data transmission circuit may transfer information in (a) one direction only, (b) either direction but one way at a time, or (c) both directions simultaneously. See duplex (telecommunications).
This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).