Telephone ring signal detector

Abstract

A telephone ring signal detector for detecting a telephone ring signal voltage on a telecommunications line connectable to at least one line telephone device. Detector includes a ring signal processor comprising a voltage translating device for providing a translated electrical parameter and an electrical parameter threshold setting device for providing a predetermined threshold reference electrical parameter value. The setting device provides a ring signal detect output signal when an electrical parameter value of the translated parameter exceeds the predetermined threshold reference electrical parameter value in a first quarter cycle time period of a first telephone ring signal cycle time period. In response to the ring signal detect output signal, a line impedance switch couples a first telephone device off-hook terminal impedance to the line to provide a first answering function, couples a detector line signal to the line and provides a simulated telephone ring signal to a telephone device output port connectable to an output telephone device. The output telephone device terminal impedance is monitored by an output line monitor to activate or deactivate a port coupling line switch which uncouples or couples the output port to the line in response to a second answering function by the output telephone device. The detector also receives and processes a caller line signal to activate an audible alerting signal. When in response to the alerting signal a person activates the line telephone device, an input line monitor uncouples the first off-hook terminal impedance from the line in response to a second telephone device off-hook terminal impedance associated with the telephone line device.