Abstract: An apparatus for testing modular telephone cables in an unenergized multiline distribution system including a multiline trunk cable and one or more connected individual line cables. The apparatus includes a power unit with circuitry connecting one or more of the wires of an individual telephone line cable with battery or other current source and an indicator unit having a plurality of indicating devices such as incandescent lights or, preferably, light emitting diodes and circuitry connecting each potentially active wire in the trunk cable with one of the indicating devices. By various circuit schemes, identification of the individual line wires in the trunk cable, polarity of the connection and continuity of the wires between the end units can be determined from the indicating devices.