Abstract: A method and apparatus for monitoring the status of a speech connection between central office lines in a private exchange system may be constructed with a controlling unit for controlling a connection between a network and a corresponding central office line to perform a speech connection between first and second central office lines; a line interface unit for interfacing the first and second central office lines under the control of the controlling unit; a network unit for connecting the first and second central office lines to each other under the connection control of the controlling unit; and a speech monitoring the status of unit for monitoring the speech connection during the connection of the first and second central office lines, by directly detecting the presence or absence of a signal from the first and second central office lines inputted thereto through the network unit without interrupting the connection between the first and second central office lines and for outputting the speech connection s

Abstract: A circuit for resetting a system controller includes a level detector and a watch-dog circuit. The level detector compares a first reference voltage with a supply voltage provided to the system, and provides output of a first reset signal indicating that the controller is in an abnormal state in dependence upon the comparison between the first reference voltage and the supply voltage. The watch-dog circuit compares a second reference voltage with a voltage exhibited by the first reset signal, and provides output of a second reset signal to the controller to reset the controller in dependence upon the comparison between the second reference voltage and the voltage exhibited by the first reset signal. A connector provides the first reset signal from the level detector to the watch-dog circuit.