KR20000043863A - Preventer for false use of public phone - Google Patents

Abstract

PURPOSE: A preventer for a false use of a public phone is provided to prevent the false use by operating a dial pulse of the public phone, so that a charge leakage of the public phone can be prevented, The preventer is provided to recognize general managers for reliability of charging in executing a card phone, so that a self-supply can be activated. CONSTITUTION: A preventer for a false use of a public phone comprises a call circuit(12), a dial tone multiple frequency(DTMF) detector(15), and a title circuit(18). The call circuit(12) forms a speech path with an exchange office, and cuts the speech path when receiving a control of the title circuit, and decided to be an abnormal call. The DTMF detector(15) detects a DTMF signal, when transmitting signal generated from the DTMF generator(15), to an office line.

Description

Public telephone fraud prevention device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing illegal use of public telephones, and to an apparatus for preventing illegal use of public telephones for making intercity and international calls at city rates by operating hook switches or dial pulses of public telephones.

In general, public telephones set up local, intercity, international, and information rates (114,00794) and analyze their own dial numbers to determine whether they are local, intercity, international, or guided. The charging signal (polarity inversion) sent from the network is detected by the CO line and reduced by the set rate.

By the way, a certain number of people use the characteristics of the public telephones to operate dials and hook switches of public telephones, which are recognized as local calls to public telephones, and international and long distance calls to exchanges. It is occurring.

For example, before the dial tone is input from the switching center, dial '0' number in advance so that the switching center recognizes the long distance or international call, and the public telephone does not recognize the '0' number. It is to pay less.

As a result, there are many shortages in the amount of money collected in public telephones where the payment is made in coins, and in the case of card-type public telephones, leakage of income is caused by illegal international calls. There is an urgent need for a device to prevent this.

In addition, such a public telephone illegal use prevention device is indispensable in the system where a general manager installs / operates a public telephone (card type) in order to reduce a lot of efforts and costs that are put into the management of the public telephone and to supply a public telephone. It is recognized as a matter.

The present invention, in view of the conventional problems and requirements as described above, apparatus which does not affect the call quality in the fundamental prevention of the illegal use of the form of operating the public telephone itself, such as dials and hook switches of public telephones And to provide a device that prevents fraudulent use without modifying the current exchanger or installing a separate sensing system to implement this.

That is, in order to achieve the above object, a dial tone multi-frequency (hereinafter referred to as DTMF) signal generated when a user dials, and when the signal is transmitted through a line, is obtained by detecting the signal in the line transmission part. The two signals are compared, and then the connection to the call is controlled according to whether the two signals match.

In addition, in order to achieve the above object, additionally, a means for transmitting a confirmation tone to the fraud prevention apparatus, and when a dial tone is input from an exchange station or a DTMF signal is output by a user, By sending the confirmation tone in the confirmation signal, it is possible to determine whether the public telephone is used by the switching center and the separate confirmation means.

In addition, in order to achieve the above object, the DTMF signal generated by the DTMF generating unit is not generated even if the user presses the dial in advance until there is a dial tone input from the switching center, so that the DTMF signal due to the illegal input is switched by the switching center. Do not recognize it.

In addition, in order to achieve the above object, the frequency of various tones (eg, ring tone (DT), busy tone (BT), relay line runaway sound (RBT), etc.) transmitted from the exchange is analyzed to analyze the operation state of the exchange and the public telephone. This is to ensure that there is no error in handling international calls at local rates.

1 is a block diagram showing a public telephone illegal use prevention device according to the present invention.

Figure 2 is a flow chart illustrating the operation of the illegal use prevention apparatus according to the present invention.

<Description of Symbols for Major Parts of Drawings>

10: illegal use of public telephone prevention device 11: hook on / off detection unit

12: call circuit unit 13: switch signal confirmation unit

14: DTMF generating unit 15: DTMF detecting unit

16: confirmation tone generating unit 17: charging signal detection unit

18: subject fisherman

An apparatus for operating as described above is a device for preventing unauthorized use of a public telephone including a hook on / off detection unit and a charging signal detection unit.

A communication circuit section which forms a communication path with the switching center and cuts the communication path when it is determined to be an abnormal call attempt under the control of the main controller;

A DTMF detection unit for detecting the DTMF signal when a signal generated from the dial tone multiple frequency (DTMF) generation unit is transmitted to the trunk line;

And controlling a main unit, and comparing a signal detected by the DTMF detection unit with a signal dialed by the user, and including a main control unit for controlling the operation of the call circuit unit.

In addition, in order to achieve the above object, if a dial tone (DT), a busy tone (BT), or a relay line runaway (RBT) signal is detected among the exchanger signals inputted through the trunk line from the switching center, the main controller It is characterized in that it is added to the exchange signal confirmation unit for notifying the call circuit unit of the public telephone to switch to the redial mode to initialize.

In addition, in order to achieve the above object, when a dial tone is detected from the switching center, a confirmation tone generating unit for transmitting a specific confirmation tone of the non-voice band signal and allowing the switching station to determine that a public telephone is used is added. It is characterized by.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a block diagram showing a public telephone illegal use prevention device 10 according to the present invention, which is mounted and used inside a public telephone.

A hook on / off detector (11) for detecting a hook on / off signal of a public telephone (not shown);

A communication circuit section 12 which forms a communication path with the switching center and cuts the communication path when it is determined by the present invention to be an abnormal call attempt;

A switch signal checking unit 13 for checking switch signals such as a dial tone (DT), a ring tone (BT), and a relay line runaway sound (RBT) input from the switching center through the trunk lines L1 and L2;

A DTMF generator 14 for generating a DTMF signal for the number dialed by the user and transmitting the DTMF signal to the trunk line;

A DTMF detection unit 15 for detecting a DTMF signal transmitted to the trunk line at a transmission end;

A confirmation tone generating unit 16 for transmitting a signal in a non-audio band when a dial tone from the switching center is detected;

A charging signal detection unit 17 for detecting a charging signal (inversion pulse) input from the switching center according to the call state;

The main control unit controls the units, and compares the signal detected by the DTMF detection unit 17 with the signal dialed by the user (the signal generated by the DTMF generating unit 14) to control the operation of the call circuit unit 12. The part 18 is provided.

At this time, when the DTMF generating unit 14 generates a DTMF signal corresponding to the telephone button input by the user, the DTMF generating unit 14 does not generate the button even if the button input is input in advance before the dial tone is input from the switching center.

The operation of the public telephone illegal use prevention device configured as described above will be described in detail with reference to the flowchart of FIG. 3.

When the user hooks off (HOOK OFF) in the public telephone and the call path is connected (S1), and then a dial tone (DT) is input from the exchange, this is a dial tone is input through the switch signal confirmation unit 13. This is confirmed, and the main control unit 18, which detects this, controls the confirmation tone generating unit 16 to send the confirmation tone to the switching center.

When the dial tone is confirmed, the operation of the DTMF generator 14 is generated to generate a DTMF signal corresponding to the dial button input by the user, and when there is no dial tone input, the call path is cut (S2).

Subsequently, as the user presses the dial, a signal generated by the DTMF generating unit 14 is transmitted through a line, and at this time, the DTMF detecting unit 15 detects the transmitted signal.

The two signals are input to the main control unit 18, and the main control unit 18 compares the two signals to determine whether they match, and then, if the two signals match, keeps the communication path. Cut (S3).

Subsequently, when the charging signal input is detected through the signal confirmation unit 13 from the exchange station while the communication path is maintained, the main control unit 18 controls the confirmation tone generating unit 16 to transmit the confirmation tone. (S4).

Through the above process, it is possible to prevent the illegal use by manipulating the dial pulse of the public telephone, and when the relay line congestion sound is input from the switching station during the operation as described above, the signal is exchanged through the exchange signal checking unit 13. Is detected, which is input to the main controller 18.

The main controller 18 receiving the signal initializes the call circuit unit 12 by switching the operation state of the public telephone to the redial mode.

On the other hand, when generating the confirmation tone in the confirmation tone generating unit 15, in order to prevent the illegal use of city, long distance, international calls, the confirmation tone after each dial input until the third digit of the dial input by the user. By outputting it once, if the confirmation tone is not inputted at the switching center and other confirmation tone detecting means, the call path is cut off as if it is being used illegally instead of using a public telephone.

For reference, the present invention is economical advantage in the implementation of the device because the public telephone telephone circuit is used as it is except for the exchange signal confirmation unit, DTMF detection unit, confirmation tone generator and main control unit in the public telephone fraud prevention device This is easy.

As described in detail above, the present invention has an advantage of preventing charge leakage of a payphone by manipulating a dial pulse of the payphone itself, and is charged to general managers when implementing a card-type payphone system. It involves the benefit of activating the self-sufficiency because it recognizes the reliability of performance.

In addition, a preferred embodiment of the present invention is disclosed for the purpose of illustration, those skilled in the art will be able to make various modifications, changes, additions, etc. within the spirit and scope of the present invention, such modifications and modifications belong to the following claims You will have to look.

Claims (5)

In the illegal use prevention device of the public telephone provided with a hook on / off detection part and a charging signal detection part, A communication circuit section which forms a communication path with the switching center and cuts the communication path when it is determined to be an abnormal call attempt under the control of the main controller; A DTMF detection unit for detecting the DTMF signal when a signal generated from the dial tone multiple frequency (DTMF) generation unit is transmitted to the trunk line; And controlling a main unit, and comparing a signal detected by the DTMF detection unit with a signal dialed by the user, and having a main control unit controlling the operation of the call circuit unit. The method of claim 1, The DTMF generation unit under the control of the main control unit, even if the dial is input until the dial tone input from the switching center does not generate a DTMF signal corresponding to the public telephone, characterized in that the illegal use prevention device. The method of claim 1, When a dial tone (DT), a busy tone (BT), or a trunk line runaway (RBT) signal is detected among the exchanger signals input from the switching center through the trunk line, the state is notified to the main control unit, and the call circuit unit of the public telephone is redialed. The apparatus for preventing illegal use of a public telephone, characterized in that for adding a switch signal confirmation unit for initializing the switch. The method of claim 1, And a confirmation tone generating unit for transmitting a specific confirmation tone of the non-voice band signal when the dial tone is detected from the switching center so as to determine that the switching center is using the public telephone. The method of claim 4, wherein The confirmation tone generating unit transmits a specific confirmation tone every time a dial is input when the first three digits are dialed using a public telephone, so that the exchange office can determine the illegal use of local, domestic and international calls. Public telephone fraud prevention device.