TRANSIENT CONTROLLED TELEPHONE LINE CIRCUIT

摘要

The present invention relates to a line circuit for use in controlling communication connections over communication lead between a telephone switching machine and a telephone station. The circuit is adapted for a lead control between the line circuit and the telephone station. The circuit is comprised of a hold unit for connection to the communication leads from the switching machine, the hold unit being operable for maintaining a connection from the switching machine in an active noncommunication condition. A monitor is provided for monitoring the A lead. A station network transition detector is provided which is monetarily operable upon station network connection to or disconnection from the communication leads. A unit is provided for enabling the hold unit upon a detected signal on the A lead and the nonoperable condition of the station network transition detector. A signal is provided for signaling the disconnection of the station from the switching machine upon a detected signal from the A lead and upon the momentary operation of the station network transition detector.