Abstract: An interface circuit between a subscriber's telephone line and exchange control components, with a reduced current consumption in the case of a grounded cable, includes a control circuit which senses the increase in the amplitude of the longitudinal currents on the line due to the grounded cable condition and consequently controls the disconnection of the current supplied to the line. However, the line is still supplied periodically for very short periods so as to reduce as far as possible current consumption during the grounded cable condition, but to allow the control circuit to sense the removal of the breakdown and to restore the normal current supplied to the line.

Abstract: A telephone circuit, which may be monolithically integrated, for feeding a subscriber's telephone line which is coupled via the circuit to a supply voltage generator. The circuit supplies the line with an impedance having a first predetermined value up to a given value of the line current, beyond which is supplies the line with an impedance of a second value greater than the first. The circuit is electrically equivalent to a voltage generator, identical to the supply voltage generator, having circuit components solely of the resistive type connected in series therewith.