BG65528B1 - Device for subscribersæ telephone line protection from abuse - Google Patents

Abstract

The device can be applied in the communications engineering. It prevents any undesired use of the telephone line for making outgoing telephone calls in case of deliberate physical disconnection of the line and including an additional device to it and to the automatic telephone exchange. The device comprises a subscriberÆs module (1) connected to the wires of the telephone line (4) and including a current meter (1) and voltage meter (14), included in the subscriberÆs module (1) and a logical control unit (34). A module in the telephone exchange (3) connected to the wiring of the telephone line(4) is also provided, comprising a current meter (32), coordination and blocking unit (31), voltage meter (33), connected to line (4), to the current meter (32) and to the logic control unit (34), the output of which is connected to a protection contact (36), connected in parallel to the coordination and blocking unit (31). A code detector (35) is also envisaged, the output of which is connected to the logic control unit (34), as voltage converter (37), the output of which is connected to the voltage meter (33), meter (32), unit (34), the coordination and blocking unit (31) and the code detector (35). The module (1) also contains unit for coordination to telephone line (13) and supply unit (12), output connected to unit (13), to the logic processing unit (15), to meter (11) and to meter (14), the output of which is coupled to the logical processing unit (15) with a button, connected in parallel to it, for initial programming (16), the output of which is connected to unit (13).

Description

(54) UNAUTHORIZED CALL PROTECTION DEVICE

The invention relates to a device for protecting a local telephone line from unauthorized use, which is used in communications technology for the protection of local and local telephone subscribers against unauthorized outgoing or incoming use of the lines at the expense of the telephone operator or the holders of telephone posts by including them in additional devices such as telephone, fax machine, modem and more.

BACKGROUND OF THE INVENTION

A device for protecting a local telephone line from unauthorized use is known, which is designed as a subscriber module included in the "a" or "b" wire of a two-wire local telephone line, to which the telephone of a telephone post from automatic telephone exchange. The subscriber module consists of a matching and blocking unit connected to the "a" conductor, and its outputs are supplied respectively to a voltage detector, a power switch and a barrier switch whose output is fed through a delay switch to a rectifier unit connected in parallel to the wires on the telephone line. The output of the rectifier unit is supplied simultaneously to the delay switch and via the voltage detector to a power switch output connected to the delay switch input and to a logic control unit and a signal generator. Outbound, the subscriber module is connected via the wires of the telephone line to the facilities of the automatic telephone exchange / 1 /.

The disadvantage of the device for protecting the local telephone line from unauthorized use is that it does not prevent the unwanted use of the telephone line for making outgoing telephone calls in case of deliberate physical interruption of the telephone line, and connecting an additional device in it to the automatic telephone exchange between the auxiliary device and the device for protecting the local telephone line.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a device for protecting a local telephone line against unauthorized use, which prevents the unwanted use of the telephone line for making outgoing telephone calls in case of deliberate physical interruption of the telephone line and connecting an additional device therein to the automatic telephone exchange. between the auxiliary device and the PSTN device.

In accordance with the invention, this problem is solved by a device for protecting a local telephone line against unauthorized use, constructed by a subscriber module connected to one wire of a two-wire telephone line and consisting of a current meter and a voltage meter, respectively connected in series with one of the the two wires on and parallel to the telephone line and from the logic control unit. Also provided is a module in a telephone exchange connected to the wires of the telephone line irrespective of the switching polarity, consisting of a current meter and a matching and blocking unit connected in series to one of the wires, and a voltage meter connected in parallel to the telephone line and to the output of the current meter and output to the input of the logic control unit, the output of which is fed to the first open position of a protective contact connected in parallel to the matching and blocking unit. In addition, a code detector connected in parallel to the telephone line is provided, its output being fed to the logic control unit, as well as to a voltage converter whose output is fed to the voltage meter, current meter, logic control unit , the matching and blocking unit, and the code detector. In the subscriber module in series one of the wires of the telephone line includes a block for matching to the telephone line and a power unit output connected to the

65528 Bl of the block for matching to the telephone line, to the logic processing unit, to the current meter and to the voltage meter, the output of which is fed to the logical processing unit with a parallel button for its initial programming, the output of which is connected to the block for matching to a telephone line.

The advantages of the UPS device are that it is fully guaranteed to prevent unauthorized use of the UPS in all possible types of auxiliary devices, whether consecutive, parallel, through ground, through external voltage, by deliberately disconnecting the telephone line, as well as by differently selected sequences of manipulations performed with the auxiliary device and telephone in a telephone post, incl. but to it a protective device.

Explanation of the attached figure

Figure 1 is a block diagram of the device.

An exemplary embodiment of the invention

As shown in the figure, the device for protecting a telephone line from unauthorized use consists of a subscriber module 1 mounted near or inside the telephone post unit 2, and a module in a telephone exchange 3 connected to each other by a two-wire subscriber telephone line 4.

The subscriber module 1 is connected in series to the "a" conductor or "in" conductor of the telephone line 4, irrespective of the polarity of connection, by means of a current meter 11, a power supply unit 12 and a matching unit to the telephone line 13, and in parallel to the telephone post 2 - by means of a voltage meter 14. The output of the power unit 12 is supplied simultaneously to the block for matching to a telephone line 13, a current meter 11, a voltage meter 14 and to a logic processing unit 15, with a button connected thereto. for initial programming 1 6.

The module in the PBX 3, which is connected in parallel to the facilities of the automatic telephone exchange not shown in the figure, is constructed by being connected in series to one of the "a" -wires or "in" wires of the two-wire telephone line 4, block for matching and blocking 31 and a current meter 32 which is connected in parallel to a telephone exchange by means of a voltage meter 33, the output of which is supplied to a logic control unit 34 to which an output detector of code 35 is connected. The output of the logic control unit 34 is fed to the first open position of the protective contact 36, to which the second open position is fed the input of the detector code 35 connected in parallel to the telephone line 4. The output of the current meter 32 is fed to the input of the logic control unit 34, and the protective contact 36 is connected in parallel to the matching and blocking unit 31. In addition, a voltage converter 37 is provided, to which a voltage meter 33, a current meter 32, a logic control unit 34, a block for a galvanically separated output are provided. according to assisted by its consultant and block 31 and detector code 35.

The operation of the device is as follows.

The device prevents attempts to misuse the local loop 4 by plugging in an additional device 5, which may be a telephone, fax machine, modem, etc., in the area between the subscriber module 1 and the module in the PBX 3.

From the subscriber module 1, a digital code in the out-of-band frequency region is continuously transmitted through the block for matching to the telephone line 13 in the telephone line 4 continuously from the time of borrowing to its release. This code contains data that is measured by the current meter 11 and the voltage meter 14, then processed in the logic processing unit 15. This data is encoded with a special individual changing polynomial and is used to calculate the protected subscriber telephone feature. line 4 as well as the identification number. The transmitted encoded data is received by the module in the PBX 3, which is mounted in the automatic PBX itself, not shown in the figure, by means of a code detector 35, from where the data arrives in the block.

65528 Logical Control Block 34 in which they are decoded. There are also data from the current meter 32 and the voltage meter

33. After processing the data from the subscriber module 1 and module 2, the characteristic of the subscriber telephone line 4 is calculated in its logic control unit 34. The subscriber module 1 is fed from the telephone line 4 through a power unit 12 and the module in the telephone exchange 3 is powered by a voltage converter 37 galvanically separated from the power supply voltage of the PBX not shown in the figure.

Upon initial switching on of the device according to the invention, a one-time procedure is performed for initially measuring and storing the characteristics of the local telephone line 4. The procedure is started by activating the initial programming button 16 in the subscriber module 1. During its execution, in the code transmitted by the subscriber module 1, information was added indicating the module in the PBX 3 for performing initial measurement and storing the characteristics of the subscriber telephone line. th 4. After the procedure, the module in PBX 3 apart loop and the device is ready for normal operation.

In the normal operation of the device, continuously from the time of borrowing until the release of the telephone line 4, the module in the PBX 3 processes the data for the current characteristic of the telephone line 4 and compares with the stored information in the initial measurement procedure, comparing continuously and the identification part of the code. In case the identity is compared when comparing the data, the protective contact 36 remains closed and the device allows the use of the telephone line 4.

When attempting to misuse telephone line 4 by switching on an additional device 5, the current characteristic of the telephone line 4 changes regardless of the location and mode of inclusion of the additional device 5. In this situation, the continuous comparison made by the logic control unit 34 of the current characteristic with the stored characteristic, a difference is made, as a result of which the logic control unit 34 performs a procedure for protecting the telephone line 4, in which The contact line 36 and the telephone line 4 are disintegrated via the matching and blocking unit 31. This prevents the attempt to misuse it, by occupying the telephone line 4 again through the matching and blocking unit 31 and immediately transmits it. of a call signal in the frequency spectrum, the purpose of which is to make it impossible to use telephone line 4 or to perform a new tone dialing and to warn about the protective measures taken. If impulse dialing follows, the above described protection procedure is repeated. The security procedure is also performed when a mismatch in the identification part of the code or no code at all is detected by the logic control unit 34. Upon termination of the attempt to misuse the telephone line 4 by switching on an additional device 5, the possibility of normal use of the line from the telephone post 2 shall be automatically restored in the event that no further action is required.

The essence of the operation of the device consists in the fact that from the subscriber module 1, through the block for matching to telephone line 13 in the telephone line 4, a corresponding digital code in the out-of-frequency frequency spectrum is continuously transmitted from the time of borrowing to its release. This code contains the measured data in the subscriber module 1 of the current meter 11 and the voltage meter 14, which data is encoded with a special individual variable polynomial and then submitted for processing and identification by the logic processing unit 15.

The device described in this way absolutely prevents any attempt to misuse a local telephone line 4 to make free outgoing telephone calls at the expense of an unsuspecting telephone post 2 by intentionally and improperly including an additional device 5 between the subscriber module 1 and the module in telephone exchange 3.

65528 Bl

In addition, the additional device 5 included at the same time to the telephone set assigned to a telephone post 2 and its corresponding facilities in the automatic telephone exchange does not interfere with the normal use of the telephone line 4 by the subscriber, and does not interfere with the occupation and release of the telephone line 4 itself.

The device is applicable for tone and pulse dialing, as it does not cause interruption of the telephone line during its use, prevents it from entering into additional noise and interference or deteriorating the quality of the established connection, does not interfere with, suppress or deform automatic telephone exchange to the subscriber's telephone post billing impulses, which can be - 12-kHz, 16-kHz or for charging with reverse polarity of the telephone line. On the other hand, the device does not have adverse effects in taking, releasing and using the telephone line in an incoming direction, such as suppression of the received call signal from the automatic telephone exchange, receiving signals for identification of the calling subscriber, as well as for the normal use of the telephone line. from the subscriber in the absence of additional interference in the telephone line.

Using the device does not affect the performance of tests and tests of the subscriber telephone line performed from the automatic telephone exchange, and its operation is independent of the different types of cables used for telephone lines in the telecommunication network, or the polarity of connecting a telephone line. line to the device.

Claims (1)

Claims 1. A device for protecting a telephone line against unauthorized use, constructed by a subscriber module connected to one conductor of a two-wire telephone line and consisting of a current meter and a voltage meter, each of which is respectively connected in series to one of the two wires of telephone line and in parallel to it, and a logic control unit, characterized in that the device also includes a telephone exchange module (3) connected to the wires of the telephone line (4), consisting of a current meter (3 2) and a matching and blocking unit (31) connected in series to one of the wires of the telephone line (4) and a voltage meter (33) connected in parallel to the telephone line (4) and to the output of the current meter (32) ) and outgoing to the input of a logic control unit (34), the output of which is fed to a first open position of a protective contact (36) connected in parallel to the matching and blocking unit (31), wherein a code detector (32) is provided. 35), connected in parallel to the telephone line (4), its output being fed to the logical unit control (34), as well as a voltage converter (37), the output of which is fed to a voltage meter (33), a current meter (32), a logic control unit (34), a matching and blocking unit (31), and a code detector (35), wherein in the subscriber module (1) in series one of the wires of the telephone line (4) includes a matching unit (13) to the telephone line (4) and a power unit (12) output connected to the matching unit (13) to a telephone line (4), to a logic processing unit (15), to the current meter (11) and to the meter rezhenie (14) whose output is fed to the unit for logical processing (15) in parallel connected to the switch for initial programming (16) the output of which is connected to a unit for co-ordination to a telephone line (13).