Abstract: A circuit protection device designed to protect a pair of electrical circuits by fracturing at such time as an overcurrent condition has occurred in a first of the circuits, this novel device comprising a substantially flat substrate of non-conductive, frangible material upon which a resistive component and a fuse conductor reside in an adjacent relationship on a common surface. The resistive component is part of a first circuit, and the fuse conductor is part of a second circuit. The resistive component, at the time of an overcurrent therethrough, becomes hot and causes a heating of the near surface of the frangible substrate.

Abstract: The invention provides a tip party identification facility in association with a subscriber line interface circuit. The tip party identification facility takes advantage of a shutdown feature and the output of a common mode error amplifier of the subscriber line interface circuit. The use of this facility enables the central office to determine whether the tip party or ring party is off-hook for billing purposes.