An interface circuit interfaces a device with a line-pair. The interface circuit includes: a diode bridge having polarity-independent input terminals coupled to the line-pair, and first and second output terminals having a positive polarity and a negative polarity, respectively; a first galvanic isolation device for outputting a receive signal received on the line-pair via the diode bridge; a second galvanic isolation device receiving a transmit signal; a voltage-controlled variable resistance element connected across the positive and negative output terminals of the diode bridge; and first and second filters cascaded between the second galvanic isolation device and the voltage-controlled variable resistance element. The first filter has decoupled charge and discharge paths so as to decouple the rise time and the fall time of the transmit signal. The second filter has a voltage-dependent frequency characteristic. The voltage-controlled variable resistance element couples the transmit signal to the line-pair via the diode bridge.