Abstract: A telephone line test and display circuit for enabling a craftsperson to automatically monitor a plurality of communication aspects of a telephone line without impacting any communications that may be taking place over the telephone line being monitored includes a communication capability detection and indicator unit through which the craftsperson may observe the DC operational state (busy/idle, battery polarity, talk battery present) condition of the line by observing a pair of light emitting diodes. The light emitting diodes are color-coded in accordance with operational status conditions being monitored and are illuminated in either a steady state or flashing condition, depending upon the DC state of the line. Also contained with the test and display circuit is a frequency discriminator/display unit, having a set of light emitting diodes separate from those employed for monitoring the DC operational status of the telephone line.