Dr.Meter Phone Telephone Line Cord Tracker Network Line Cable Tester Detect continuity of the cables or wires without damaging the insulation. Track the cables or wires, and diagnose the break point. A professional & safe tool for wireman. Receiver the tone signal on the cables or wires (telephone line). Identify the state in the working telephone line (clear ring, busy). Send a single solid tone or a dual alternating tone to the object cables or wires.