MXPA99001310A - Avon telephone loop protection equipment - Google Patents

Abstract

A device for the protection of the telephone loop of a subscriber, intended to avoid the making of fraudulent calls by a third party, in which two devices are involved, one at the subscriber's home and the other at the central, both connected in series with the telephone line, constituted that of the subscriber by a pick-up detector, an encoder for code generation, and a frequency modulator of the generated code, and constituted that of the exchange by an identification coder, a demodulator, a decoder, a detector off-hook, a dialed number receiver, control means, a switch, a block of RAM memory and an output device, by means of which a code comparable to that sent by the subscriber device is selected, so that the control determines the nature of the call and whether or not to activate the switch, the fraudulent call data can be stored in the RAM and extracted by the device I left

Description

PROTECTIVE TEAM OF THE SUBSCRIBER TELEPHONE LOOP DESCRIPTIVE MEMORY The present invention relates to a system for preventing the making of fraudulent calls in the telephone subscriber loop, by personnel different from the user who contracted the service. The system allows you to store information related to the fraudulent call made, such as the time, date of the call or the number called. This invention has its application in the field of telecommunications and more specifically in that of telephony, to improve the security and the service provided to subscribers. It is known that insufficient security measures of the telephone line, in the section that goes from the central to the home of the subscriber, allow a possible fraudster can connect to the subscriber loop and make telephone calls that would be charged to the owner of the line. It is not known, on the part of these inventors, the existence of any device that solves this problem. The Subscriber Loop Protection Equipment, object of this invention, allows detecting situations of the type discussed above, and prevent calls from being imputed to the owner of the line.

DESCRIPTION OF THE INVENTION The Subscriber Loop Protection Equipment, object of this invention, is a system whose mission is to prevent the making of fraudulent calls by persons other than the user of the loop that contracts the service with the communications operator. The system consists of two parts or devices: one located in the subscriber's house and the other in the exchange that provides service to said subscriber. The functions to be performed by the system are: - Identify non-fraudulent calls as such, in a totally transparent manner from the point of view of the subscriber. - Identify fraudulent calls as such without alerting the intruder to it, both in case the subscriber is disconnected and in case it is not. - Proceed to the registration of the dialed number or the intruder, the date and time of realization of the call and, in case the progress of the call made by the intruder is allowed, the duration or the end time of the same. - Optionally, prevent the progress of the call, but keeping the line in service once the process is finished. The possible scenarios in which the system can be found are: - Call from the private subscriber installation. In this situation, the device located in the subscriber's house detects the origin of the call and sends an identification signal. The team located in the center checks that the identification code is correct and does not take any action.

- Call from an outside point of the subscriber loop. In this case, the device on the subscriber's side does not detect an off-hook at the subscriber's private installation and, therefore, does not send the identification code. The central station team checks the arrival of a call not preceded by the identification code, considers it fraudulent and performs the following actions: registration of the dialed number, date and time of the same, etc. As well as the optional disconnection of the call. - Call coming from an external point of the subscriber loop with disconnection thereof. In this situation the subscriber's device is disconnected from the network and, therefore, does not send identification code. The dialing pulses are not preceded by the identification code, so the equipment located in the central office identifies the call as fraudulent and performs the consequent actions. - Call from a different subscriber device. In this case, the call comes from a different private subscriber installation. Your device will send a different identification code and the exchange team will identify the call as fraudulent, taking the necessary actions. The identification code sent by the equipment located in the subscriber's home must be transmitted modulated on a carrier that does not interfere with the different services that can be carried out through the protected subscriber loop, such as basic telephony, telefax, teletax, piped music, data, etc. The device located in the subscriber's house is connected in series, in the private subscriber installation, having a connection interface with the subscriber and another connection interface with the loop that goes to the exchange. It is basically constituted by the following blocks: 1) .- Off-hook detector block 2) .- Encoder block 3) .- Modulator block The off-hook detector block is responsible for monitoring the subscriber line to check when a hook-off is carried out. the private subscriber installation. When this occurs, it warns the coding block of said eventuality. The coding block is the one that generates the subscriber identification signal by sending said code to the modulator block. The identification code is fixed by hardware in the manufacturing process and, therefore, can not be modified. This procedure reduces the space occupied by the code block, avoids the possibility of manipulations by the subscriber and preserves the confidentiality of the code. The modulator block is responsible for modulating the identification signal provided by the code block. It is modulated in frequency on a suitable frequency carrier. The equipment located on the side of the plant is connected in series in the telephone exchange, having two interfaces, one with the loop that goes to the subscriber and another with the central. Performs the following functions: - Supervision of the status of the line and receipt of the identification code sent by the equipment on the subscriber's side.

- Generation of fraudulent call indication when a call is not preceded by the correct identification code. - Detection of the dialed number when said indication occurs. - Recording of the dialed number, date and time of the start of the call and duration of the call, as long as the call is allowed, that is, if the option to interrupt the fraudulent call is not enabled. - Interruption of the call once the dialing is completed, provided that the option to interrupt the fraudulent call is enabled. The information related to the registered incidents can be collected from the equipment periodically by means of the connection, through a connector for that purpose, of a portable computer or some other recording device, as well as by means of the recording in the planned memory card. The equipment on the side of the plant is basically constituted by the following blocks: 1) .- Identification coder 2) .- Demodulator 3) .- Decoder 4) .- Off - hook detector 5) .- Receiver of the marked number 6). - Control 7) .- Switch 8) .- RAM memory 9) .- Output device The identification coding block allows you to select the identification code that allows you to validate the calls and that must coincide with the code sent by the team on the side of the subscriber, sending it to the decoder block. The demodulator block extracts the signal, with the information of the identification code, from the carrier on which it is transmitted in the equipment on the subscriber's side. The decoder block is responsible for checking whether the code received through the line matches the identification code assigned to the subscriber. In the event that the received identification code is not valid, the decoder block provides the control block with the fraudulent call signal, so that the latter performs the appropriate actions. The off-hook detector block monitors the subscriber line to detect when a hook-off occurs. When this occurs, it informs the control group of this eventuality, so that the latter may take the appropriate actions. The receiver block of the dialed number monitors the line so that, if a call is made, it supplies the dialed number to the control block, so that the latter carries out the appropriate actions. The control block is the one that performs the control functions of the equipment on the side of the control panel, managing the actions to be carried out with the information provided by the detector blocks of the receiver, decoder and receiver of the dialed number. It has processing capacity, through a microcontroller. It is responsible for storing the data of interest in the RAM block, for communicating to the switch block whether or not it should prevent the progress of the fraudulent call, as well as for managing communications with the output device used to remove the stored information. in the RAM block. The process that follows when a call is made is the following: - The control block receives the off-hook indication from the off-hook detector block. - The decoder block receives the subscriber identification code. If it is valid, it transmits a non-fraudulent call indication to the control block and the latter does not take any action. If the received identification code is not valid or no identification code is received, the control block identifies the call as fraudulent. - If the call is identified as fraudulent, the control block, with the data referring to the dialed digits sent by the receiving block of the dialed number, stores in the RAM block the dialed number together with the data referring to the day and start time of the call. - If the option to interrupt the call is enabled, the control block sends, once the dialing process is completed, a call blocking signal to the switch block, so that the latter blocks the progress of the call. The switch block is in charge of preventing the progress of the fraudulent call when said option is activated. The control block is responsible for communicating said order to the switch block, so that the latter opens the telephone line and prevents the progress of the call.

The RAM block is a storage device, which can be shared by several control blocks belonging to several lines, in which the data related to fraudulent calls is recorded. The output device block is the one that receives the data related to the detected incidents and that, under the control of the control block, are dumped from the RAM memory block where they are stored, through a communications line that joins the output device and control blocks respectively. The output device can be a laptop or some other recording equipment.

BRIEF DESCRIPTION OF THE DD3UJOS To complete the description that is being made and in order to help a better understanding of the invention, this descriptive report is accompanied, as an integral part of the same, two sheets of drawings in which, with an illustrative and non-limiting character, the following is represented: Figure 1.- Corresponds to the block diagram of the device located in the subscriber's house and belonging to the Subscriber Loop Protection Team, as well as its main connections. Figure 2.- Corresponds to the block diagram of the device located in the plant and belonging to the Subscriber Loop Protection Team, as well as its main connections. Figure 3.- Corresponds to the state diagram of the state machine that controls the validation of calls.

DESCRIPTION OF THE INVENTION The Subscriber Loop Protection Equipment, object of this invention, is a system whose mission is to prevent the making of fraudulent calls by persons other than the user of the loop that contracts the service with the communications operator. The system consists of two parts or devices: one located in the home of the subscriber, figure 1, and another in the exchange that provides service to said subscriber, figure 2. The functions to be performed by the system are: - Identify as such the calls not fraudulent, in a totally transparent way from the point of view of the subscriber. - Identify fraudulent calls as such without alerting the intruder to it, whether the subscriber is disconnected or not. - Proceed to register the number marked by the intruder, along with the date and time of the call, as well as the duration of the call in case the progress of the call made by the intruder is allowed. - Optionally, prevent the progress of the call, but keeping the line in service once the process is finished. Possible scenarios in which the system can be found are: - Call from the private subscriber installation: In this situation, the device located in the subscriber's house detects the origin of the call and sends an identification signal. The team located in the center checks that the identification code is correct and does not take any action. - Call from an outside point of the subscriber loop: In this case the subscriber-side device does not detect an off-hook at the subscriber's private installation and, therefore, does not send the identification code. The control panel checks the arrival of a call not preceded by the identification code, so it considers it fraudulent and performs the following actions: registration of the dialed number, date and time of the call and optional disconnection of the call, as well as the record of the duration or end of the same if the option of disconnection of the call is not enabled. - Call coming from an external point of the subscriber loop with disconnection thereof. In this situation the subscriber's device is disconnected from the network and, therefore, does not send identification code. The dialing pulses are not preceded by the identification code, so the equipment located in the exchange identifies the call as fraudulent and performs the consequent actions. - Call from a different subscriber device. In this case, the call comes from a different private subscriber installation. Your device will send a different identification code and the exchange team will identify the call as fraudulent, carrying out the consequent actions. The identification code sent by the equipment located in the subscriber's home must be transmitted modulated on a carrier that does not interfere with the different services that can be carried out through the protected subscriber loop, such as basic telephony, telefax, teletax, piped music, data , etc. As seen in Figure 1, the device located in the subscriber's house is connected in series, in the private subscriber installation, having an interface (4) for connecting to the subscriber and another interface (5) for connecting to the subscriber. loop that goes to the central. It consists basically of the following blocks: 1) .- Block (1) detector off-hook 2) .- Block (2) encoder 3) .- Block (3) modulator Block (1) off-hook detector is responsible for monitoring the subscriber line to check when an off-hook is performed in the private subscriber installation. When this occurs it warns, through the connection (6), to the block (2) coding for said eventuality. The encoder block (2) is the one that generates the subscriber identification signal by sending said code, through the connection (7) to the modulator block (3). The identification code is fixed by hardware in the manufacturing process and, therefore, can not be modified. This procedure reduces the space occupied by the code block, avoids the possibility of manipulations by the subscriber and preserves the confidentiality of the code. The modulator block (3) is responsible for modulating the identification signal that the encoder block (2) delivers to it, through the connection (7), and for sending it through the connection interface (5). It is modulated in frequency on a suitable frequency carrier.

As can be seen in Figure 2, the device located on the side of the plant is connected in series in the telephone exchange, having two interfaces, one with the loop that goes to the subscriber (17) and another (19) with the central. Performs the following functions: - Supervision of the status of the line and receipt of the identification code sent by the equipment on the subscriber's side. - Generation of fraudulent call indication when a call is not preceded by the correct identification code. - Detection of the dialed number when said indication occurs. - Recording of the dialed number, date and time of the start of the call and, when the call is allowed, that is, if the option of interrupting the fraudulent call, the duration or end of the call is not enabled. - Interruption of the call once the dialing is completed, provided that the option to interrupt the fraudulent call is enabled. - Allow calls by a guard when the equipment located on the side of the control panel is in tests even if the option to interrupt the call is enabled. Likewise, the call with the call condition in tests is registered. The information related to the registered incidents can be collected from the equipment periodically by means of the connection, through a connector for that purpose, of a portable computer or some other recording device, as well as by means of the memory card recording.

The equipment on the side of the plant is basically constituted by the following blocks: 1) .- Encoder (12) of identification 2) .- Demodulator (10) 3) .- Decoder (13) 4) .- Detector (8) of off-hook 5) .- Receiver (11) of the dialed number 6) .- Control (14) 7) .- Switch (9) 8) .- RAN memory (15) 9) .- Output device (16) The block ( 12) identification encoder, allows to select the identification code that allows to validate the calls and that must match the code sent by the equipment on the subscriber's side, sending it to the decoder block (13) by means of the connection (22). The demodulator block (10) extracts the signal, with the identification code information, from the carrier on which it is transmitted in the device on the subscriber's side and sends it, through the connection (20), to the block ( 13) decoder. The decoding block (13) is responsible for checking whether the code received through the line, and that it is delivered by the demodulator block (10) through the connection (20), coincides with the identification code assigned to the subscriber . In the event that the received identification code is not valid, the decoding block (13) provides the control block (14), through the connection (23), with the fraudulent call signal to perform the appropriate actions. The off-hook detector block (8) monitors the subscriber line to detect when a hook-off occurs. When this occurs it informs, through the connection (21), to the control block (14), of this eventuality, so that the latter carries out the appropriate actions. Through the connection (18) it prolongs the subscriber's pair to the switch block (9). The block (11) receiving the dialed number monitors the line so that, if a call is made and through the connection (24), it supplies the dialed number to the control block (14), so that the latter carries out the actions timely. The control block (14) is the one that performs the control functions of the equipment on the side of the central, managing the actions to be performed with the information provided by the blocks (8) off-hook detector, decoder (13) and receiver ( 11) of the dialed number. It has processing capacity, through a microcontroller, which allows you to control the validation of calls, access to the block (15) of RAM, and control of communications with the block (16) of the output device, in order to perform on this last the dump of the data stored in the RAM memory block (15). Likewise, is responsible for communicating to the switch block (9) whether or not it should prevent the progress of the fraudulent call. To perform the call validation control the control block (14) has a state machine, whose state diagram can be seen in figure 3, and whose functionality is as follows: - In idle state (28), the machine is waiting to receive the off-hook indication from the off-hook detector block (8). If so, it goes to the start-up state (31), as indicated by the line of arrows (37), and waits to receive, from the decoder block (13), the identification code. - If in the state (31) receives the said code and this is correct, it passes to the valid call state (29), as indicated by the line of arrows (36), waiting to receive, from the block (8) Off-hook detector, the hang indication and passes, as indicated by the line of arrows (34), to the state (28) of rest. If the code fills incorrectly or begins to receive, from the block (11) receiving the dialed number, the dialing digits before the code, is passed, as indicated by the arrow lines (44) and (42), to the state (33) of registration of the dialed digits. If hanging indication is received from the off-hook detector block (8), it is passed, as indicated by the arrow line (38), to the resting state (28). - In the state (33) the dialed digits are registered. At the end of the registration of the same, the call is allowed or it is cut off in order to enable or disable the interruption of fraudulent calls. If it is enabled, it is passed, as indicated by the arrow line (43), to the short call state (32) and the control block (14) sends an indication that it cuts the call to the switch block (9). If it is not enabled, it is passed, as indicated by the arrow line (41), to the established call state (30). In the state (33) it is also possible to receive hanging indication from the off-hook detector block (8). In this situation, as indicated by the line of arrows (39), the resting state (28) is passed.

- In the cut call state (32) the state machine is waiting to receive, from the off-hook detector block (8), the hang indication to pass, as indicated by the arrow line ( 35), to the resting state (28). - In the established call state (30), the state machine remains waiting to receive, from the off-hook detector block (8), the hang indication to pass as indicated by the line of arrows (40), to the state (28) of rest. Taking a look at figure 2, we see the process that follows when a call is made, which is as follows: - The control block (14) receives, from the off-hook detector block (8), the off-hook indication by means of the connection (21). - The decoder block (13) receives the subscriber identification code. If it is valid, it transmits, through the connection (23), a non-fraudulent call indication to the control block (14), and the latter does not take any action. If the received identification code is not valid or identification code is not received, the control block (14) identifies the call as fraudulent. - If the call is identified as fraudulent, the control block (14), with the data referring to the dialed digits sent by the block (11) receiving the dialed number, stores in the block (15) of RAM the dialed number together with the data referring to the day and time of the start of the call, as well as the duration or end of the same if the option to interrupt the call is not enabled.

- If the option to interrupt the call is enabled, the control block (14) sends, once the dialing process is completed, a call blocking signal to the switch block (9), so that the latter blocks the progress of the call. call. - If the equipment located in the control panel is in tests, the progress of the call considered as fraudulent is allowed, even if the interruption condition of the call is set. In this situation, the call is registered with the test call condition. The switch block (9) is responsible for preventing the progress of the fraudulent call when said option is activated. The control block (14) is responsible for communicating, through the connection (25), said order to the switch block (9), so that the latter opens the telephone line and prevents the progress of the call. The block (15) of RAM is a storage device, which can be shared by several control blocks belonging to several lines, in which the data related to the fraudulent calls is recorded. A bus (26) connects the RAM block (15) with the multi-line control blocks (14). The block (16) of the output device is the one that, upon request, receives the data relative to the detected incidents and that, under the control of the control block (14), are overturned from the RAM block (15) where they are stored, through a communication line (27) joining the blocks (16) output device and (14) control, respectively. The output device can be a portable computer or some other recording equipment, and can be shared by more than one subscriber line. It can be located in a remote place or not. The data that is dumped are the following: - Identification of the line on which the fraudulent call was made. - Number marked by the intruder. - Attempt time of the fraudulent call. End time of the call or duration of the call, as long as the option of not blocking the call is enabled. - The test call condition if the equipment on the side of the control panel is in a test situation.

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. - Subscriber telephone loop protection equipment, designed to protect the telephone loop of a subscriber against possible fraudulent calls made by a person other than the one who contracted the service, characterized in that it is constituted from two separate and independent devices , of which one of them, or subscriber device, can be installed in the home of the subscriber in series with the telephone line by using a first interface (4) to the subscriber and a second interface (5) to the loop that goes to the central, is composed, preferably, by a block (1) detector of the situation of off-hook in series with the line, in charge of verifying that in the installation of the subscriber has made an off-hook; an encoder block (2), whose input has been electrically connected to the aforementioned block (1) by means of a connection (6), and a modulator block (3), whose input has been electrically connected to the output of the previous block (2) by means of a connection (7), and whose output is electrically connected to the line itself, while the second device, or switchboard device, is also connected in series with the telephone line, with the collaboration of a first interface (17) towards the subscriber loop and a second interface (19) to the central station, and preferably comprises a pick-up detector block (8), in series with the line; a block (9) switch, in series with the line; a block (10) with the demodulator function, whose input is connected to the line and whose output has been connected to an input of a decoder (13), to which the output of an identification coder (12) has also been connected; a means (11) receiving the dialed number, electrically connected to the line; a control means (14), internally provided with a microcontroller for the control of the various associated functions, and to which the detector block (8), the switch block (9), the receiver block (11), have been electrically connected; the dialed number and the decoder block (13), by means of the respective connections (21, 25, 24, 23); a block (15) of RAM memory, and a connection (27) for an output device (16). 2.- Subscriber telephone loop protection equipment according to claim 1, characterized in that the detection by the block (1) of an off-hook operation of the subscriber's telephone determines the performance of the encoder block (2) for the generation of an identification code corresponding to that subscriber, of characteristics determined by the hardware of the system itself, so that the identification signal from the code block is frequency modulated in the modulator block (3), on a carrier of predetermined frequency , from where it is returned to the line for shipment to the central. 3.- Telephone subscriber loop protection equipment according to claim 1, characterized in that the monitoring of the line carried out by the off-hook detector block (8), corresponding to the device of the control panel, detects any carried-out hooking operation, with the consequent sending of the pertinent signal to the control block (14), so that if the latter receives from the decoder block (13), before the block (11) receiving the dialed number detects the dialed numbers and communicate to said detector block (14), indication that the call identification code is correct, the call is considered correct and said block (14) does not take any action, whereas if said identification code does not match the information received from the decoding block (13), the call will be considered fraudulent and the control block (14) will proceed, in case the condition of i is activated. call interrupt and after having received from the block (11) the markings numbers, to indicate to the switching block (9) the cut of the call, while in case the previous interruption condition of the call is not activated, the block (14) control will take note of the relevant data and store them in block (15) of memory, without taking any action on said block (9) switch; finally, if after detecting the off-hook situation, the dialed numbers are received in the block (14) without having received an indication, from block (13), of receiving a correct or incorrect code, block (14) will consider the fraudulent call and act in the manner indicated for such situation. 4.- Subscriber telephone loop protection equipment according to claim 3, characterized in that the activation of the test operation condition determines that any call considered as fraudulent is stored with the test call condition, without the control block (14) perform any action on said switch block (9), by virtue of the prevalence of the test condition over that of call interruption. 5.- Subscriber telephone loop protection equipment according to the preceding claims, characterized in that the memory block (15) can be used as a multiple storage device for the data relating to several lines, by means of its electrical connection to the respective control blocks (14) with the use of an appropriate bus (26). 6.- Subscriber telephone loop protection equipment according to the preceding claims, characterized in that it also incorporates an output device (16), in particular a laptop or some other registration equipment, located at a remote location or no, intended to display the data relating to the incidents detected by the data dump from the memory block (15), under the control of the control block (14), and because said device (16) output is susceptible to use by more than one subscriber line through the respective control means (14).