Telephone device, telephone line monitoring device and method

Abstract

A telephone line monitoring device is connected to a telephone line and adjacent to a telephone device using the telephone line. The telephone line monitoring device includes a rectifying circuit for generating a corresponding direct current voltage according to an effective voltage of the telephone line; a first controller for generating a first control signal when the direct current voltage is lower than a predetermined voltage; a second controller for detecting an operating state of the telephone device and generating a second control signal when the telephone device is operated; a load booster for pulling down the effective voltage of the telephone line when enabled; and a first switch circuit for disabling the load booster whenever receiving the second control signal, and enabling the load booster when receiving the first control signal while not receiving the second control signal. A monitoring method and a telephone device are also provided.