Telecommunication line circuit including a Herter bridge (R o - R5) with a first pair of terminals (STB, SRA) coupled to a bidirectional 2-wire line, a second pair of terminals (STA, SRB) coupled to an exchange, and a third pair of terminals (A,B) where longitudinal currents are eliminated from sensed signals, as well as a ringing generator (RC) that may be coupled across the second pair of terminals which is coupled to a receive leg (RX) of a 4-wire exchange circuit and, through switching means (sw30/31) to the ringing generator while the third pair of terminals is coupled to a transmit leg (Tx) of the 4-wire exchange circuit.