Method and monitoring system for monitoring at least one subscriber line

A method for signaling to a central facility a fault of at least one subscriber line connected to a switching center via a respective connection line having a UK0 interface includes permanently activating the at least one subscriber line using the switching center. Each of the at least one subscriber line is monitored using a respective monitoring device looped into a UK0 interface on the respective connection line. A connection to the central facility is established via a separate subscriber line in response to a fault of a first of the at least one subscriber line detected by the respective monitoring device. An item of information related to the first subscriber line is transmitted to the central facility.

BACKGROUND

The present invention relates to a method for signaling a fault of at least one subscriber line to be monitored to a central facility as well as to a monitoring system for monitoring such a subscriber line.

The acceptance of public telecommunications networks among the customers essentially depends on their reliability of operation and performance. Therefore, a major task of the network operators is to monitor established connections or connections to be established within these telecommunications networks and, if necessary, to perform a fault diagnosis.

One possibility of monitoring ISDN telecommunications networks is to measure and log ISDN basic accesses at the S0interface at the telephone subscriber end (see, for example, the operating instructions of the ISDN S0basic access measuring and testing device Pegasus from the Festo Didactic KG company, Esslingen, as of 02/95; page 85).

German Patent DE 197 29072 describes a method for measuring or logging an ISDN basic access which can also be executed independently of the telephone subscriber to be monitored. This is achieved by opening the UK0interface at a point of the connection line that is convenient for measurement or logging. In the opened UK0interface, the line signals arc converted into IOM signals, and the IOM signals are in turn converted into S0frames. Consequently, all data of the tapped S0interface are available to already existing S0measuring devices at the point where the connection line is opened.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and a monitoring system with which at least one subscriber line can be continuously monitored and with which a central security facility can be immediately alerted in case of a fault. with which a central security facility can be immediately alerted in case of a fault.

The present invention provides a method for signaling to a central facility a fault of at least one subscriber line, each of the at least one subscriber line being connected to a switching center via a respective connection line, each connection line including a UK0interface. The method includes: permanently activating the at least one subscriber line using the switching center; monitoring each of the at least one subscriber line using a respective monitoring device looped into a UK0interface of the respective connection line; establishing a connection to the central facility via a separate subscriber line in response to a fault of a first of the at least one subscriber line detected by the respective monitoring device; and transmitting an item of information related to the first subscriber line to the central facility.

In order to be able to monitor the subscriber line, the switching center keeps the subscriber line permanently active, i.e., in the rest state, predetermined test messages (keep alive, polling) are continuously transmitted from the switching center to the subscriber line and vice versa, for example, every ten seconds, so that an interruption of the connection line can always be detected in this manner. The permanent activation can also refer to layer1, i.e., the synchronization of the UK0interface can be used for monitoring. A monitoring device, which is looped into the UK0interface of the corresponding connection line, monitors the at least one subscriber line. This is done, for example, by checking the test messages, which are transmitted during the activation, for their presence on the connection line. If the monitoring device detects a fault of the at least one subscriber line to be monitored, for example, an interruption of the connection line, a connection to the central facility is established via a separate subscriber line, in particular, of a public telecommunications network. Subsequently, a fault message and/or an item of information related to the subscriber line, such as the address or call number of the disturbed subscriber line, is/are transmitted to the central facility.

In this manner, it is possible to continuously monitor a subscriber line and to transmit a fault message and the address of the disturbed subscriber line to a central security facility in case of a fault.

The monitoring device is expediently looped into the UK0interface of the respective connection line near the switching center, i.e., in the same building.

If the intention is to use the method to monitor a plurality of subscriber lines assigned to the switching center and to measure and/or log their states in case of a fault, initially, a first connection set-up is initiated at this or another external terminal device via the separate subscriber line preferably to a DTMF (multifrequency dialing) controllable switching matrix, subsequent to the transmission of the fault message and/or of the item of information related to the subscriber line to the central facility. Thereupon, the switching matrix is programmed as a function of the item of information related to the subscriber line in such a manner that a measuring device, which is connected to the separate subscriber line, can be connected to the disturbed subscriber line via a UK0tap of the respective subscriber line that is contained in the monitoring device. Subsequently, the connection is released again. After that, a second connection set-up is initiated at the central facility or at the other external terminal device via the separate subscriber line to the measuring device, which is now caused to measure and/or log the state of the disturbed subscriber line and to transmit the results via the existing connection to the central facility or to the external terminal device.

Preferably, the subscriber lines to be monitored and the separate subscriber line are ISDN basic accesses. In this case, the measuring device is designed to create a D channel protocol of the S0interface of the ISDN basic access. To this end, however, it is required to connect each connection line to the switching matrix via the UK0tap. The UK0tap of each monitoring device provides that the data tapped at the UK0interface of the connection line is converted into an S0frame which can be processed by the measuring device. Such a UK0tap is known from German Patent DE 197 29072.

The present invention provides a monitoring system for monitoring at least one subscriber line which is connected to a switching center via a connection line which features a UK0interface. Looped into the UK0interface of each connection line to be monitored that is connected to the switching center is moreover a device for monitoring the associated subscriber line. Each monitoring device is connectable to a device for generating a fault message and/or an item of information related to the subscriber line, the latter device, in turn, being connected to a separate subscriber line. Via this separate subscriber line, it is possible for the device for generating a fault message and/or an item of information related to the subscriber line to establish a connection to a central facility to transmit the fault message and/or the item of information related to the subscriber line. The device for generating a fault message and/or an item of information related to the subscriber line can be, for example, a DS 7500 device from the effeff company.

Except for the central facility, all devices and units can be accommodated in the building of the switching center.

Advantageously, each monitoring device has a detector as well as a controllable switch which, when the detector detects a fault of the associated subscriber line, connects the respective monitoring device to the device for generating a fault message and/or an item of information related to the subscriber line. In this manner, the device for generating a fault message and/or an item of information related to the subscriber line is caused to generate the fault message and/or the item of information related to the subscriber line about the disturbed subscriber line and to transmit it to the central facility.

In order to be able to measure and/or log at least one subscriber line, at least one monitoring device is connectable to a measuring device which is connected to the separate subscriber line. Thus, it is possible for the measuring device to measure and/or log the state of the disturbed subscriber connection, which is tapped via the monitoring device, and to transmit the results via a public network to the central facility or to another external device.

To permit monitoring of a plurality of subscriber lines, a switching matrix is connected between the monitoring devices and the measuring device. Moreover, a DTMF remote control device is connected to the separate subscriber line and to the switching matrix, the DTMF remote control device being able to be dialed up by the central facility or another external device via the separate subscriber line for controlling the switching matrix.

If the item of information related to the subscriber line includes the address of a disturbed subscriber line, then the switching matrix can be programmed via the DTMF control device as a function of the address in such a manner that the measuring device can be connected to the corresponding UK0tap.

If the subscriber lines are ISDN basic accesses, each monitoring device features a UK0tap, the S0interface of the monitoring device being connected to the switching matrix. In this manner, the tapped S0interface of the disturbed ISDN basic access can be tapped via the switching matrix and connected to the measuring device. The measuring device is capable of analyzing the D, B1or B2channels of an ISDN connection.

Furthermore, it should be mentioned that, besides the ISDN connections mentioned here, it is also possible to monitor standard fixed lines and direct data connections which are provided with a UK0interface.

DETAILED DESCRIPTION

FIG. 1shows a monitoring system which is universally denoted by10and is connected near a digital switching center40via a monitoring device70at an opened UK0interface20of a connection line30and via a monitoring device72at an opened UK0interface22of a connection line32. Although only two connection lines are connected to digital switching center40, it is obvious that a plurality of connection lines can be connected to digital switching center40and to monitoring system10.

At the subscriber end, connection lines30and32are terminated at the ISDN basic access with a network termination device50and52, respectively. Each network termination device50,52is connected to an ISDN telephone60or62, respectively.

At this point, it should be mentioned that monitoring system10can be suitable not only for monitoring connection lines featuring ISDN basic accesses but also for monitoring standard fixed lines and direct data connections.

Monitoring devices70and72each contain detectors (not shown) with which, for example, an interruption on respective connection line30or32can be detected as a fault. Moreover, each monitoring device70,72features a potential-free contact80and82, respectively, via which a fault of the associated subscriber line that is detected by the corresponding monitoring device70,72can be signaled to a signaling device150for generating a fault message and/or an item of information related to the subscriber line, referred to as signaling device150hereinafter. Moreover, each monitoring device70,72has a UK0tap (not shown), which is known per se and via which the monitoring devices can be connected to a switching matrix90. The mode of operation of the UK0tap is known from German Patent DE 197 29072, which is included herein by reference. The UK0taps provide that the signals to be tapped at UK0interfaces20and22are converted into S0frames which, in turn, can be processed in a conventional S0measuring device100, which is connected to switching matrix90. As will still be explained in greater detail below, the state of each ISDN basic access, in particular, the D channel of an ISDN connection, can be measured and logged using S0measuring device100. Moreover, measuring device100is connected to an ISDN basic access110via which a connection can be established via a public network to a central facility120or to an arbitrary terminal device equipped with an ISDN card. In this manner, as will still be explained in greater detail below, it is possible to transmit the measuring results and logs of measuring device100to central facility120.

Also connected to ISDN basic access110is, for example, a DTMF remote control device130, possibly via a conventional terminal adapter140.

On the output side, DTMF remote control device130is connected to switching matrix90. The control of switching matrix90through DTMF remote control device130can take place, for example, via central facility120. For that purpose, the central facility must be able to generate signals according to the multifrequency dialing method. A method, which is suitable for this, is disclosed in German Patent 199 34 622, which is is hereby incorporated by reference herein.

In the following, the mode of operation of monitoring system10will be explained in greater detail. First of all, the two ISDN basic accesses of connection lines30and32are assumed to be continuously monitored with the aid of a permanent activation. Due to the triggered permanent activation, predetermined test messages are transmitted back and forth between digital switching center40and ISDN telephones60and62approximately every ten seconds, also in the rest state. As long as the detectors of monitoring devices70and72detect the presence of these test messages, monitoring system10is in the so-called “monitoring mode”. However, as soon as no test messages are detected any more on one of connection lines30or32, i.e., an interruption of the connection line is detected, monitoring system10goes into the signaling and measuring mode with respect to this connection line. In this context, it is assumed, for example, that connection line30has been interrupted. In response to the interruption of connection line30, the detector of monitoring device70closes potential-free contact80, as a result of which a fault of the ISDN basic access of connection line30is signaled to signaling device150. Signaling device150recognizes the disturbed ISDN basic access and the call number thereof from the actuation of potential-free contact80. Thereupon, signaling device150establishes a connection, via ISDN basic access110, to central facility120and transmits a corresponding fault message as well as the call number of the disturbed ISDN basic access to central facility120. The connection between signaling device150and central facility120can be released after the transmission of the fault message and the call number. Now, a monitoring person at central facility120initiates a connection set-up via ISDN basic access110to DTMF remote control device130and enters the call number of the disturbed ISDN basic access at central facility120, the call number being transmitted to DTMF remote control device130by multifrequency tones. In response to the received call number of the disturbed ISDN basic access, DTMF remote control device130controls switching matrix90in such a manner that measuring device100is able to measure and/or log the corresponding subscriber line via the UK0tap. Subsequently, the monitoring person releases the connection to DTMF remote control device130again, and initiates a second connection set-up via ISDN basic access110to measuring device100. Measuring device100is now connected to the UK0tap of the corresponding monitoring device (70,72) and is consequently able to analyze and log the D, B1or B2channels of the disturbed ISDN basic access. The current states, results and logs of the disturbed ISDN basic access can be transmitted by measuring device100via ISDN basic access110to central facility120and there be displayed by the monitoring person on a display. In this manner, the monitoring person can immediately decide whether it is required to send a service technician to the customer of the disturbed ISDN basic access or whether remote maintenance is possible. After the fault has been eliminated, monitoring system10is reset to the monitoring mode with respect to connection line30, that is, potential-free contact80of monitoring device70is opened again.

Although in the present example, only a measuring device100is connected to switching matrix90and only one ISDN basic access110is used, it is conceivable to connect a plurality of measuring devices100to switching matrix90and to connect the measuring devices to central facility120via a plurality of ISDN basic accesses.

Thanks to the described monitoring system10, it is possible to continuously monitor one or a plurality of subscriber line(s) and to transmit a fault message and the address of the disturbed subscriber line to a central facility in case of a fault. Moreover, it is possible to directly influence the monitoring system in many ways from the central facility via the public network. For instance, it is conceivable for call forwarding to be activated in switching center40for a disturbed ISDN basic access.