Telephone interface-test device

Claim 1

A telephone line tester comprising: switching means having a double poled input adapted to be coupled to a telephone central office line and at least first and second double pole outputs for selectively coupling the double pole input to one of said double pole outputs; a plug jack coupled across said first output, and said plug jack having receptacle means for receiving an electrical plug having at least first and second electrical conductors, whereby a telephone user circuit may be coupled and uncoupled to said electrical conductors; electrical circuit means connected across said second output and said circuit means including a constant voltage impedance and signal impedance connected in series and an illuminating impedance for effecting and fully powering the turn-on of a dial tone on said telephone line when connected to said telephone line; amplification means including a bias input connected across said constant voltage impedance, a signal input connected across said signal impedance for amplifying dial tone signals across said signal impedance; and a signal-to-sound reproducer connected across said output of said amplification means; whereby, with said switching means in a first said position, said jack provides coupling between any user telephone circuit connected to a telephone central office line enabling telephone service, and when said switching means is in said second position, said amplification means is powered and a dial tone on said telephone line is caused to appear on said telephone line and reproduced, and said illuminating impedance is illuminated without application of other operating bias.