A method for signaling to a central facility a fault of at least one subscriber's connection to be monitored, wherein the at least one subscriber's connection is connected to a switching center via a local line (30, 32) that includes a U K0 interface (20, 22), the method comprising the steps of: - permanently activating the at least one subscriber's connection to be monitored, by the switching center; - monitoring the at least one subscriber's connection using a monitoring device (70, 72) that is looped into the U K0 interface (20, 22) of the respective local line (30, 32); - establishing a connection to the central facility via a separate subscriber's connection in response to a fault of the at least one subscriber's connection to be monitored detected by the device; and - transmitting a fault message and/or a subscriber's connection related information to the central facility; characterized by the steps of: subsequent to the transmission of the fault message and/or the subscriber's connection related information to the central facility, initiating a first call set-up at the central facility or at another external terminal device to a controllable switching matrix via the separate subscriber's connection; programming the switching matrix as a function of the subscriber's connection related information so that a measuring device connected to the separate subscriber's connection can be connected to the monitoring device (70, 72) of the respective local line (30, 32), wherein the switching matrix is connected between the monitoring devices (70, 72) and the measuring device; releasing the connection; and initiating a second call set-up at the central facility or at the other external terminal device via the separate subscriber's connection to the measuring device which is capable of measuring and/or logging the state of the disturbed subscriber's connection and of transmitting the state to the central facility or to the other external device. - permanently activating the at least one subscriber's connection to be monitored, by the switching center; - monitoring the at least one subscriber's connection using a monitoring device (70, 72) that is looped into the U K0 interface (20, 22) of the respective local line (30, 32); - establishing a connection to the central facility via a separate subscriber's connection in response to a fault of the at least one subscriber's connection to be monitored detected by the device; and - transmitting a fault message and/or a subscriber's connection related information to the central facility; characterized by the steps of: subsequent to the transmission of the fault message and/or the subscriber's connection related information to the central facility, initiating a first call set-up at the central facility or at another external terminal device to a controllable switching matrix via the separate subscriber's connection; programming the switching matrix as a function of the subscriber's connection related information so that a measuring device connected to the separate subscriber's connection can be connected to the monitoring device (70, 72) of the respective local line (30, 32), wherein the switching matrix is connected between the monitoring devices (70, 72) and the measuring device; releasing the connection; and initiating a second call set-up at the central facility or at the other external terminal device via the separate subscriber's connection to the measuring device which is capable of measuring and/or logging the state of the disturbed subscriber's connection and of transmitting the state to the central facility or to the other external device. subsequent to the transmission of the fault message and/or the subscriber's connection related information to the central facility, initiating a first call set-up at the central facility or at another external terminal device to a controllable switching matrix via the separate subscriber's connection; programming the switching matrix as a function of the subscriber's connection related information so that a measuring device connected to the separate subscriber's connection can be connected to the monitoring device (70, 72) of the respective local line (30, 32), wherein the switching matrix is connected between the monitoring devices (70, 72) and the measuring device; releasing the connection; and initiating a second call set-up at the central facility or at the other external terminal device via the separate subscriber's connection to the measuring device which is capable of measuring and/or logging the state of the disturbed subscriber's connection and of transmitting the state to the central facility or to the other external device.