The RJ Jack Identifier is designed to aid network technicians and MIS personnel in the identification of the equipment connected to the modular jacks found throughout the work place. It will aid in determining what type of equipment is connected to the other end of the wall plate or cable by being able to detect cable terminators on all 4 pairs of a T568A/B wired jack or plug, and by being able to detect voltage on the center pair of phone lines.