Two-wire circuit
From Wikipedia, the free encyclopedia
A two-wire circuit is characterized by supporting transmission in two directions simultaneously, as opposed to four wire circuits, which have separate pairs for transmit and receive. In either case they are twisted pairs. Telephone subscriber lines are almost all two wire, while trunks and switching are almost entirely four wire. The conversion is done in a hybrid coil in the telephone exchange, sometimes as part of a four-wire terminating set.
Contrast with four-wire circuit.
