Telephone loop monitoring and isolation system

Abstract

A telephone loop monitoring and isolation device which can be connected to a wireless telephone subscriber unit providing an interface between an analog or digital central station network and the internal telephone wiring of a subscribers premises. The device is also operable with a cable telephone subscriber unit. The device provides passive real time loop status information as well as loop isolation if the voltage across the loop falls below a predetermined level. When normal loop impedance conditions are restored, the subscriber loop is automatically reconnected to the subscriber telephone unit. The device is effective for examining open circuit and abnormal impedance conditions and provides loop status information to the telephone subscriber. The system of the invention also has an alarm enhancement in that it will provide an alarm status indication to a monitoring center, such as a police department or the like, while still maintaining communication capabilities, even during an existing active telephone communication.