A method and a system for impairment line testing are provided. The method includes electrically connecting a first terminal of a measurement device, which may be a time domain reflectometer, to both wires of a twisted wire pair of a telephone line, which interconnects a telephone line card with a subscriber. The second terminal of the measurement device is electrically connected to a common reference, which may be the ground reference. Then, the method includes performing an impairment testing on the telephone line from the measurement device toward the subscriber.