Abstract: A subscriber connection circuit comprises heat resistors which can be bridged in a low-ohmic manner and an indication circuit which effects different indication functions. Four different operating states are possible, characterized by the nature of the feed, the switching threshold for the indication circuit, and the actuation of a filter element for the indication circuit, two of which operating modes represent the ringing phase and the ringing interval. During the ringing interval, the nature of the feed and the threshold voltage are identical to those in the conversation operating state, but in contrast thereto the filter element is actuated.

Abstract: In the monitoring of various loop states of subscriber connection lines, a decentralized individual subscriber analysis device is employed which is connected to the subscriber connection line via a voltage divider whose divider ratio is modified accordingly, for which purpose feed resistors of different values are used. For establishing loop closure as a result of a call, during the ringing phase the feed-in points for feed current and ringing alternating current are selected to be such that the ringing alternating voltage components at the inputs of the analysis device compensate one another and therefore do not influence the result of analysis.

Abstract: A subscriber connection circuit comprising an improvement for analyzing the reliability of operating states of a subscriber connection circuit without involving a substantial increase in cost over those used in known telecommunication systems which employ a central analyzing device for a plurality of subscriber connection lines.