| 摘要 |
PURPOSE:To use only one supervising circuit and a loop forming resistance with respect to plural terminal equipment by converting the digital information from the control device of a switchboard to a voltage value, and generating a desired detecting threshold. CONSTITUTION:A titled system is provided with a circuit 1 for supplying a DC current to a subscriber terminal equipment 11 connected in parallel to a telephone set 15, a supervising circuit 5 for discriminating the state of the telephone set 15 and the equipment 11 by the variation quantity of the DC current, a communication circuit 3 to the telephone set 15 and the equipment 11, and a D/A converter 16 for generating a detecting threshold of the supervising circuit 5 basing on the terminal classifying digital information sent out of the control device of a switchboard. In this state, in accordance with the instruction of the control device, a detecting threshold corresponding to a classification of a terminal is generated by the digital information and the converter 16, and by this detecting threshold, a state of the telephone set 15 and the equipment 11 is discriminated. |
