CN1212549A - Device for preventing telephone subscriber line from being stolen - Google Patents

Abstract

A device for preventing telephone user lines from being stolen. The device detects the output potential of the telephone rectifier through a theft detection circuit to know that the telephone user line has been stolen, thereby sending a signal to trigger the telephone dialer, enabling the telephone's call network and loop load, and sending an alarm signal to the telephone user line to interfere with the dialing or call of the phone of the theft user. At the same time, the alarm signal is fed back to the telephone amplifier circuit of the telephone, and sent out by the loudspeaker to form a warning sound to inform the user. The present invention uses the theft detection circuit in conjunction with the existing resources of the telephone to achieve the purpose of interfering with the theft user and notifying the user at the lowest cost.

Description

Device for preventing telephone subscriber line from being stolen

The present invention relates to a device for preventing telephone subscriber lines from being stolen, in particular to a device for preventing telephone lines from being stolen by using a telephone dialer to emit an alarm signal to interfere with the thief and notify the user.

Phone theft is an annoying problem that often causes considerable damage and is not easy to prevent. And the telephone subscriber line being stolen is exactly wherein common a kind of, because the user is difficult to detect whether there is the pirate of outdoors to use its telephone line, so can't take precautions against.

One of the ways to solve the above-mentioned difficulties is to install a detection device. Figure 1 shows a known technology, which is to install a detection device on the telephone line. Once the thief uses the phone, an alarm sound will be triggered to notify the user that his telephone subscriber line Misappropriation.

The phone 100 includes the components of a general phone and a detection and alarm device. The general telephone line is connected to other lines from the outside line terminal 101 through a rectifier 102, including hook switch 103, receiver detection circuit 104, dialer 105, keyboard 106, loop control telephone 107, communication network and loop load 108, and expansion Audio telephone amplifier circuit 109, these all are the basic devices that constitute the telephone set, and the already clear knowledge of those who are familiar with this technology will not be described in detail here.

The detection and alarm device part is to install a fraud detection circuit 110 connected to the output end of the rectifier 102 . When all the telephones are on-hook, that is, the telephone loops are all in a high-impedance state, the output terminal of the rectifier 102 is at a high potential, such as 48 volts. If the thief steals the telephone line, the loop of the outdoor parallel unit 112 is connected, and the output potential of the rectifier 102 drops to a low potential, such as 12 volts. This potential change is detected by the fraud detection circuit 110, and sends a fraud detection signal UVD to start a sound signal device 111, such as an oscillator or a sound integrated circuit (IC), and its signal output is sent to the buzzer 113 to send an alarm sound. The user then learns that the telephone line has been stolen.

Although the above-mentioned method solves some problems, it is not perfect. For example, the device only provides an alarm function, that is, it only notifies the user itself, and does not wish to have any blocking effect on the embezzler; The ringer 113 needs to increase a lot of cost, which is relatively unfavorable in industrial utilization (commercialization); what is more serious is that no matter the indoor parallel machine or the outdoor parallel machine will touch the device, once the device is installed, it will cause failure to connect. Other indoor extensions. Therefore, it is necessary to improve the technology for preventing telephone subscriber lines from being stolen, so as to avoid above-mentioned various defects.

Therefore, what the present invention intends to achieve is to propose a low-cost device for preventing telephone subscriber line from being stolen, so as to eliminate the disadvantages of the above-mentioned prior art, and achieve the purpose of disturbing the pirate and warning the user at the lowest cost.

In detail, the main purpose of the present invention is to provide a device for interfering with stolen telephones, which can interfere with dialing or talking on the telephone of the fraudster by sending an alarm signal to the telephone subscriber line.

Another object of the present invention is to provide a device with an alarm function, which sends out an alarm signal through the loudspeaker of the telephone to inform the telephone user that his subscriber line has been stolen.

Another object of the present invention is to disclose a low-cost device for preventing phone subscriber line from being stolen, which is to make full use of the existing resources of the phone to interfere with the thief and notify the user, so that the cost of the overall device is reduced to a minimum.

Yet another object of the present invention is to propose a device that allows extensions to be connected in parallel to prevent telephone subscriber lines from being stolen, that is, the device allows telephone users to use extensions in parallel, so that the phone still maintains normal functions.

In order to achieve the above-mentioned purpose, the technical solution of the present invention is to use a misuse detection circuit to connect the rectifier and the dialer of the telephone respectively. The dialer enables the call network and loop load of the phone, and sends a periodic alarm signal to the telephone subscriber line to interfere with the dialing or talking of the phone of the thief.

Moreover, the alarm signal is fed back to the amplifier loop of the telephone set, and sent out by the amplifier to form a warning tone, informing the user that his subscriber line has been stolen.

In addition, an extension circuit state detection circuit is used to connect in series between the subscriber line and the extension terminal connected to the subscriber line in parallel, by which it can detect that the extension connected to the extension terminal is used and send a signal to make an alarm for misuse. Function is not touched.

The technical scheme of the present invention cooperates with the existing resources of the telephone set with the embezzlement detection circuit, and can achieve the purpose of interfering with the embezzler and notifying the user under the condition of the lowest cost.

The descriptions of the attached drawings are as follows:

Fig. 1 is a prior art, wherein discloses a kind of embezzlement detection mode;

Fig. 2 shows the situation of indoor parallel machine and outdoor parallel machine (stealer) of the present invention;

Fig. 3 is an embodiment of the present invention;

Fig. 4 is the operation flowchart of the present invention;

Fig. 5 is an operation timing diagram of the present invention.

The features and effects of the present invention can be better understood by the following embodiments and accompanying diagrams.

The telephone paralleling situation of the present invention is shown in Figure 2, and the main telephone 201 in the indoor 200 is provided with outside line connection terminal hole and extension connection terminal, provide and connect the outdoor telephone subscriber line and other indoor parallel machines (extensions) respectively 202, and it is a thief to install the outdoor parallel machine 203 by telephone subscriber line outdoors.

Fig. 3 shows an embodiment of the present invention, the phone 300 is connected to other lines via a rectifier 302 through an outside line terminal 301, including a hook switch 303, a handset detection circuit 304, a dialer 305, a keyboard 306, a loop control phone 307, and a communication network And the loop load 308, and the loudspeaker telephone amplifier loop 309 etc., are still the same as the existing telephone, so it is not much to illustrate.

The feature of the present invention is that the output terminal of the rectifier 302 is connected with a tamper detection circuit 310 to detect the output potential of the rectifier 302 , and the tamper detection circuit 310 provides a tamper detection signal UAD to the dialer 305 .

In this embodiment, the dial mute pin XMUTE is used as the connection between the fraud detection signal UAD and the dialer 305 . The dial mute pin XMUTE is generally used as a mute output control pin when dialing, and in this embodiment is designed as a two-way input and output control pin, which is automatically set as an input pin for fraud detection under standby (when the phone is not in use) Signal input, when the phone is in use (dialing or talking) is automatically set as the output control pin for mute control.

Selecting the dial mute pin XMUTE as the input of the embezzlement detection signal UAD is not a limitation of the present invention, and the connection pins of the embezzlement detection signal UAD and the dialer 305 can also be used for other different design choices, such as using keyboard pins, retaining output and input pins Bits or other available pins can also achieve the same purpose.

When all the telephones are in standby mode, the output terminal of the rectifier 302 is a high potential (about 48 volts), and the embezzlement detection signal UAD is logic 1 at this moment; At this time, due to the formation of the loop of the outdoor parallel machine 312, the output of the rectifier 302 drops to a low potential (about 12 volts), causing UAD to switch from logic 1 to logic 0, and then triggering the loop start control pin of the dialer 305 (such as PO, HDO, HFO, etc.), that is, the loop control circuit 307 and the amplifier loop 309 of the amplified telephone are activated, and the communication network and the loop load 308 are enabled.

After the loop is formed, set the XMUTE pin as an output function and output a low potential signal (mute), and at the same time, the DTMF pin sends an alarm signal, which is transmitted to the telephone subscriber line through the communication network and the loop load 308, which becomes an interference signal Interfere with the dialing or calling of the outdoor parallel machine 312. This alarm signal is fed back to the amplifier circuit 309 of the loudspeaker telephone at the same time, and is sent out by the loudspeaker to form a warning sound to inform the user that his subscriber line has been stolen.

The alarm signal provided by the dialer 305 has many different options, such as a single frequency signal, a music signal, or any signal that the dialer 305 generates by itself enough to interfere with dialing and conversation, or a dual-tone multiple frequency signal or pulse signal for telephone dialing, However, in order to prevent the dual-tone multi-frequency signal or pulse signal during the interference period from being mistaken for a normal dialing sequence by the public switching network, the start code of the interference signal excludes the dual-tone numbers (0-9) dialing keys as much as possible. Multiple frequency or pulse signal.

The alarm signal sent by the above-mentioned DTMF pin is a signal with a cycle T, and this cycle is called the alarm interference cycle. When the alarm interference period is over, the dialer 305 will automatically return the loop start control pin, such as PO, HDO, HFO, etc., to the initial state, close the phone loop, and automatically set the mute control pin XMUTE as the input of the tamper detection signal Detect pin in order to re-detect the signal from the UAD. If the UAD signal is still logic 0 at this time, indicating that the stolen phone 312 is still in use, the dialer 305 will start the alarm interference cycle again. If the UAD signal becomes logic 1 at the end of the alarm interference period, indicating that the fraudulent phone 312 has been hung up, then the dialer 305 returns to the initial detection state.

During the alarm disturbance period, if the microphone of the telephone set 300 is picked up, the dialer 305 will automatically end the alarm disturbance period, and through the closing of the hook switch 303, the microphone detection circuit 304 sends a signal to the dialer 305 to activate the telephone loop, so that Generally dial and receive calls, or monitor the state of the stolen phone 312.

During the above-mentioned alarm interference period, although the dialer 305 opens the loop of the phone, but this loop is not opened through a program of normal use of the phone, such as picking up the microphone, etc., so the dialer 305 will automatically close the keyboard 306 to make the key invalid. Do not interrupt the alarm interference signal.

The relationship between main signals such as the fraud detection signal UAD and the alarm interference period will be described in more detail later.

Existing inspection of the internal circuit of the embezzlement detection circuit 310, this embodiment uses an RC charging and discharging circuit as the detection circuit. When the output of the rectifier 302 is at a high potential, the Zener diode ZD1 is turned on, and a logic 1 level is obtained at the UAD pin through appropriate voltage division by the resistors R1 and R2. The diode D1 can isolate the interaction between other components in the fraud detection circuit 310 and the communication network and the loop load 308 .

The function of the extension circuit state detection circuit 311 and its internal circuit will be described below. In order to achieve the extra function of parallel connection to the indoor extension, the extension connection terminal 313 is parallel connected to the subscriber line, and the extension loop state detection circuit 311 is connected in series between the two. When the extension connected to the extension terminal 313 is in use, the loop current flows through the resistor R4 to generate a voltage drop, and the optocoupler PHO1 is turned on through the rectifier BR1 and the resistor R5. Although the output potential of the rectifier 302 drops to 12 volts at this time, the conduction of the optocoupler PHO1 keeps UAD at a logic 1 level, so that the UAD signal will not be accidentally triggered by the dialer 305 because the subscriber line is used by an extension. Alarm signal, that is, the present invention allows users to use parallel extensions. Also, the use of PHO1 also has the effect of an isolation circuit. When PHO1 is turned on, R3 has a current limiting function. Prevent large current from VDD to XMUTE pin through PHO1, D1 when XMUTE pin outputs low potential level.

The internal circuits of the above-mentioned embezzlement detection circuit 310 and extension circuit state detection circuit 311 are only embodiments, and are not limitations of the present invention. For those familiar with circuit technology, it is obvious to make various designs for the same function. , still without departing from the spirit of the present invention.

FIG. 4 shows the detailed operation process of the phone 300, please refer to FIG. 3 together.

Under normal conditions, the phone is in a standby state, that is, step 400 is waiting for an external command to activate the phone, such as picking up the handset (Off-Hook) or pressing the handset function (Handfree).

Once the signal for enabling the phone is detected, the process jumps to step 406, and the dialer 305 starts the call loop, and sets the input pin XMUTE of the fraud detection signal UAD to the state of the output control function to dial or answer the call.

Then enter step 407, if the dialer 305 detects the signal of the end of the call, such as hanging up the phone or ending the hands-free function, then the input pin XMUTE of the fraudulent detection signal UAD is set to the detection state of the fraudulent detection signal input, Simultaneously execute step 408 to close the call loop, and return to the state of step 400 to continue waiting for the command to activate the phone. The above is the general normal use process of the phone 300 .

In addition, the phone is waiting for the step 400 of enabling the phone, and at the same time it is waiting for the command of fraud detection, that is, step 401 .

Once the phone circuit of the thieves is formed and the subscriber line is detected as being stolen, it will enter step 402, and the dialer 305 will automatically start the circuit of the machine to supply the power requirements of the dialer 305 and other devices in the phone, and simultaneously transmit the detection signal of the piracy The input pin XMUTE of UAD is set to the output function control state of normal dialing, and an alarm signal is sent by the dual-tone multiple frequency signal pin DTMF as an interference signal.

The alarm interference signal operates according to the preset cycle period of the dialer 305. When the alarm interference cycle is over, step 403 enters step 408, and the dialer 305 sets the pin XMUTE to the detection state of the detection input and turns off at the same time. Talk loop, and get back to step 400 and wait for the state of enabling the phone command.

In this way, if the thief continues to use the subscriber line, the operation process of the phone will automatically execute step 400→step 401→step 402→step 403→step 408→step 400→and so on.

During the default cycle alarm interference period of the dialer 305, if the dialer 305 detects that the phone 300 itself activates the telephone command, that is, enters step 404 from step 403, then executes closing the alarm interference signal and cycle, that is, step 405, and then enters normal The operation flow of the phone 300 is step 406→step 407→step 408, etc. If the thief is still using it, the phone 300 can start monitoring at any time.

If the phone 312 of the hijacker has been turned off during the warning interference cycle, then after the dialer 305 finishes the warning interference cycle, it will automatically return to the initial detection state of step 408→step 400, and the detection signal of misappropriation does not exist now. , so the dialer 305 ends the action of this loop detection alarm interference, until the pirate loop is formed again.

The timing sequence of fraud detection and alarm interference is shown in Figure 5, please also refer to Figure 3 together.

When the outdoor parallel machine 312 is in use, the tamper detection signal UAD of the tamper detection circuit 310 is switched from logic 1 to logic 0. After this signal triggers the dialer 305 to execute for a Tdb time, the PO (HFO, HDO) pin rises from low potential to high potential, making the loop of the phone 300 conduction, and at the same time, the DTMF pin of the dialer 305 sends an alarm signal with a period of T to the phone The loop is used as a signal to interfere with the thief, and this signal is fed back to the amplifying loop 309 of the telephone set 300 or the receiver of the handset as an alarm. T 1.5 seconds in the present embodiment.

The above-mentioned period T is automatically set by the dialer 305. When the interference period ends, the PO (HFO, HDO) pin of the dialer 305 drops from a high potential to a low potential, and the telephone 300 circuit is automatically closed, and after a time of Tdb Check the signal of UAD pin again. When Tdb ends, if the UAD signal is still logic 0, the action of the disturbance period T is repeated. The Tdb time is a time to prevent malfunction caused by input signal jitter.

Moreover, the dual-tone multiple frequency (DTMF) alarm interference cycle T shown in FIG. 5 is composed of a sequence of symmetrical cycles of Toff and Ton. In the present embodiment, Toff Ton is 250 milliseconds (ms), and the pattern of its signal is that the "#" (or " ^* ") number key of the dial key is the starting code, and follows the secondary "8" key, That is, the three signals "#, 8, 8" are a cycle T.

If the outdoor parallel machine 312 is on-hook during the alarm interference period T, the UAD signal will not be converted from logic 0 to logic 1 immediately because the loop of the phone 300 itself is turned on, so after the alarm interference period T is over, the dialer 305 The PO (HFO, HDO) pins drop from high potential to low potential, automatically close the phone 300 circuit, and when the Tdb debounce sequence ends, it can detect that the UAD signal has changed from logic 0 to logic 1, indicating that the stolen phone 312 has hung up. At this time, the alarm interference period ends.

As mentioned above, during the alarm interference period T, if the thief has hung up, the UAD signal cannot return to logic 1 due to the formation of the loop of the phone itself, but when the alarm interference period T ends, the dialer 305 will automatically activate the loop The control pin returns to the initial state, closes the telephone circuit, and makes the UAD signal return to logic 1. Therefore, the alarm interference period must be designed to an appropriate length. If the period is too long, it will not be possible to immediately detect the action of the thief hanging up. According to common people's habits, the alarm interference period is preferably about 1 to 5 seconds.

In the timing sequence of Figure 5, the oscillator OSCO of the dialer 305 oscillates according to the internal timing requirements of the dialer 305 during the period T and the debounce time Tdb, and stops oscillating when the loop of the phone 300 is closed and UAD is detected as logic 1 .

In the sequence of Fig. 5, if the phone 300 itself detects a command to activate the phone, such as lifting the microphone or starting the hands-free handset, the above sequence will be reset, and the phone 300 will be in a state of normal use, and the sequence of this state It is a prior art and will not be described in detail here.

The above is to illustrate the characteristics of the present invention by means of the embodiments, and its purpose is only to enable those skilled in the art to understand the content of the present invention and implement it accordingly, rather than to limit the patent scope of the present invention. Therefore, all those who do not depart from the present invention Equivalent modifications or modifications completed in the suggested spirit should still be included in the scope of the patent application described below.

Claims (15)

1, a kind of device that prevents fraudulent use of telephone subscriber line, it is characterized in that comprising and usurp rectifier and the dialer that testing circuit connects phone respectively, this usurps testing circuit is that mat detects the output potential of this rectifier to learn this fraudulent use of telephone subscriber line, thereby touch this dialer, make the speech path network and the loop load activation of phone, and send an alarm signal and to this telephone loop, become the alarm interference signal, to disturb the dialing or the conversation of appropriator phone.

2, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this alarm signal more feedbacks to the hands free telephone amplifier circuit of phone, is sent by loudspeaker and forms caution sound.

3, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this usurps testing circuit and being connected of this dialer is that reach the quiet control pin position of this dialer of mat.

4, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this usurps testing circuit and being connected of this dialer is that reach the keyboard pin position of this dialer of mat.

5, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this usurps testing circuit and being connected of this dialer is that the reservation of this dialer of mat is exported into the pin position and reached.

6, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 or 2 is characterized in that this alarm signal is the dual-tone complex frequency signal that is provided by this dialer, and the initial code of this alarm signal is the dual-tone complex frequency signal beyond the digital code.

7, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 or 2 is characterized in that this alarm signal is the pulse signal that is provided by this dialer.

8, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 or 2 is characterized in that this alarm signal is the single-frequency that provided by this dialer number.

9, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 or 2 is characterized in that this alarm signal is the music signal that is provided by this dialer.

10, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 or 2 is characterized in that this alarm interference signal is the signal with cycle.

11, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 10, after it is characterized in that this dialer is usurped the testing circuit triggering by this, and after should alarming the end cycle of interference signal, all delay the time of beating, the beginning starts the loop start control signal of this dialer.

12, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this usurps testing circuit and be to use RC to charge and discharge circuit to learn this fraudulent use of telephone subscriber line with the potential change that detects this rectifier output end.

13, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1 is characterized in that this usurps testing circuit and comprise that the RC filter circuit filters this signal of usurping testing circuit of input to remove noise.

14, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 1, it is characterized in that more comprising that an extension set binding post is connected on this subscriber's telephone line, and be connected in series an extension set loop state testing circuit between this telephone loop and this extension set binding post, this extension set loop state testing circuit also connects this and usurps testing circuit, wherein this extension set loop state testing circuit detects extension set that this extension set binding post connected when being used, and just sends a shutdown signal and usurps testing circuit to this and make it can't touch this phone dialer.

15, the device that prevents fraudulent use of telephone subscriber line as claimed in claim 14 is characterized in that this extension set loop state testing circuit to be mat one optical coupler produces shutdown signal with the extension set detection signal conversion of input exporting this to and usurping testing circuit.

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