JPH0832693A - Providing method for interception preventive service - Google Patents

Abstract

PURPOSE:To provide an interception preventive service without regard to the presence of a interception preventing function on the side of a communication opposite side. CONSTITUTION:An equipment 4 on the side of an interception preventive station provided with interception preventing decoding and encoding functions is connected to an exchange switch 5. Then, at the time of judging a signal to be a control signal to the connection line 3 of an equipment 7 on the side of an interception preventive terminal on the other side from calling information from the subscriber line 3 of a telephone set A provided with an equipment 1 on the side of the interception preventive terminal, the exchange switch 5 is connected to the subscriber line 6 of a telephone set B not by way of an equipment 4 on the side of an interception preventive station. But when the signal is judged to be a control signal to the non-connection line of the equipment 7 on the side of an interception preventive terminal from mentioned calling information, the exchange switch 5 is connected to the subscriber line 8 of a telephone set C by way of the equipment 4 on the side of the interception preventive station.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for providing a wiretapping prevention service to a subscriber terminal. With the development of telephone exchange technology, various subscription services have come to be provided to subscribers. That is, services such as an answering machine service, a call waiting service, and a speed dial service are provided, and these service functions can be provided on the subscriber terminal side or the exchange side.

Further, as the number of subscribers has increased and the telephones have been used more conveniently, the number of false telephones and mischievous telephones has increased, and countermeasures against them have become necessary. For this reason, it has been attempted to give the telephone terminal a preventive function or change the telephone number on the exchange side so as not to inconvenience the subscriber.

One of them is an eavesdropping prevention service, which prevents recent conversations between subscribers from being eavesdropped for some reason, and prevents eavesdropping on important telephone conversations between subscribers in advance. The number of subscribers has increased, and eavesdropping prevention services have been reviewed to prevent crime.

[0004]

2. Description of the Related Art Conventionally, in order to prevent wiretapping of an analog telephone, a wiretap prevention device is added to both telephone sides of a telephone call, or a phone with a wiretapping prevention device is used on both sides, so that a subscriber line or exchange is performed. The station prevents both parties from eavesdropping on both calls.

As the wiretapping prevention device, there are a device using a spectrum reversal technique and a device using a low bit coding technique. The telephone subscriber can talk by ordinary analog voice. Even if they eavesdrop on the line, they cannot hear because of the anomalous voice and noise, and the confidential talk between the subscribers is maintained.

FIG. 6 shows a conventional wiretapping prevention method. In the figure, 31 is a telephone A, 32 is a telephone B, 33 is a telephone C, 34 is a wiretapping prevention device for the telephone A, 35 is a wiretapping prevention device for the telephone B, 36 is a telephone exchange network, and 37, 38, 39 are subscribers. The line, 40 indicates the bypass of the wiretapping prevention device. It is assumed that the telephone set A and the telephone set B are provided with an eavesdropping prevention device, and the telephone set C is not added.

When a call is made from the specific telephone set A to the specific telephone set B, since the eavesdropping prevention device is added to both sides, even if the telephone line is tapped by the subscriber line 37 or the subscriber line 38 or the telephone exchange network 36. The secret story is kept. When a call is made from the specific telephone A to the ordinary telephone C, the eavesdropping device 34 is short-circuited by the bypass 40 by the button operation of the subscriber.

[0008]

According to the conventional method, as shown in FIG.
It is necessary to add an eavesdropping prevention device or function to both terminals making a call as shown in, and eavesdropping prevention is limited only when communicating with a specific partner. That is, eavesdropping can be prevented in a call between the telephone A and the telephone B, but in a call between the telephone A and the telephone C, the eavesdropping prevention device cannot be provided because the telephone C has no eavesdropping prevention device.

If the telephone set C is called without bypassing the telephone set A, since the telephone set C does not have the function of decoding the wiretapping prevention signal, the conversation of the telephone set A can be heard with the voice being irregular. Can not. Therefore, an eavesdropping prevention function cannot be realized for an unspecified subscriber.

[0010] Recently, cordless telephones equipped with a confidential communication function are also provided, but this only makes it difficult to intercept communication in the wireless section between the slave unit and the master unit.
It cannot have any effect when wiretapping is performed on the wired part between the base unit and the exchange.

It is an object of the present invention to provide a method for implementing an eavesdropping prevention function even in communication with an unspecified partner in a telephone eavesdropping prevention service.

[0012]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, 1 is a device for preventing wiretapping of a telephone A, 2 is a subscriber line, 3 is a subscriber circuit of the telephone A, 4
Is an eavesdropping prevention side device, 5 is an exchange switch, 6 is a subscriber circuit of the phone B, 7 is an eavesdropping prevention terminal device of the phone B,
Reference numeral 8 indicates a subscriber circuit of the telephone C, and 9 indicates a subscriber line. The wiretapping prevention terminal side device 2 is connected to the telephone A, the wiretapping prevention terminal side device 7 is connected to the telephone B, and is not connected to the telephone C.

The eavesdropping prevention station side device 4 is connected to the exchange switch 5 of the station, has an eavesdropping prevention decoding function and an eavesdropping prevention encoding function, and uses the calling information from the subscriber circuit 3 for the telephone set A.
The presence or absence of connection to the wiretapping prevention terminal side device 7 is determined, and the connection configuration of the exchange switch 5 is controlled according to the determination result.

If it is judged from the calling information from the subscriber circuit 3 that it is a control signal to the connection line of the wiretapping prevention terminal side device 7,
The exchange switch 5 is connected to the subscriber circuit 6 of the telephone B without passing through the wiretapping prevention station side device 4, and the wiretapping prevention terminal side device 7 is connected.
If it is determined that the control signal is to the non-connection line, the exchange switch 5 is connected to the subscriber circuit 8 of the telephone C via the wiretapping prevention station side device 4.

[0015]

The telephone A is provided with the wiretapping prevention device / function, and the telephone B is similarly connected with the telephone B having the wiretapping prevention device / function and is connected in the same manner as in the conventional case. The wiretapping prevention encoding / decoding function enables normal analog calls between the telephone A and the telephone B, but other subscribers cannot eavesdrop on the telephone call due to anomalous signals on both subscriber lines. .

Telephone A equipped with a wiretapping prevention device / function
When a call is made with the telephone C that does not have an eavesdropping prevention device / function, the eavesdropping prevention decryption function works on the subscriber line of the telephone A by the eavesdropping prevention decryption function because the eavesdropping prevention station side device 4 is used on the station side. , No other person can eavesdrop on the call. Although it is possible to eavesdrop on the subscriber line on the side of the telephone C, there are few opportunities for eavesdropping by others because of the unspecified line.

[0017]

FIG. 2 shows an embodiment of a block diagram of the wiretapping prevention apparatus of the present invention. FIG. 2A shows a wiretapping prevention device on the terminal side, and FIG. 2B shows a wiretapping prevention device on the station side. There are various kinds of secret talk techniques used in the wiretapping prevention device, but in this embodiment, a method using a low bit rate coding technique will be described.

In the wiretapping prevention device on the terminal side of FIG. 2A, 11 is a wiretapping prevention device (terminal side), 12 is a memory circuit, and 13
Is a control circuit, 14 is a timing extraction circuit, 15 is a Psyselup coding / decoding circuit, 16 is a randomizing circuit, 17 is a modem circuit, 18 is a telephone, 19 is a subscriber line, and 20 is an exchange.

The wiretapping prevention device 11 on the terminal side is a general telephone 18
The upstream voice signal from (1) is converted into a 3.45 Kbps digital signal by the low-bit-rate encoding circuit, which is a Psyserpu encoding / decoding circuit 15. The converted digitized voice is subjected to processing such as bit rearrangement based on a certain regularity in the randomizing circuit 16 in the next stage, and together with various control signals generated from the control circuit 13 with the exchange. , Is input to a modem circuit 17 which is a modulation / demodulation circuit for converting into an in-band analog signal, and is sent to the exchange 20 side via a subscriber line 19.

The processing such as bit rearrangement in the randomizing circuit 16 is carried out in order to improve the confidential communication performance. The information in the control signal is linked to the randomizing circuit on the exchange side in the same manner. Achieve conversion regularity. Also,
Prepare multiple types of regularity and use the timing extraction circuit 14
It is possible to further improve the confidentiality by appropriately changing it according to the conditions such as the timing.

In the eavesdropping prevention apparatus on the exchange side of FIG. 2B, 21 is an eavesdropping prevention decoding apparatus, 22 is a modem circuit, 23 is a randomizing circuit, 24 is an encoding mutual conversion circuit, 25 is a control circuit, and 26 is A memory circuit, 27 is a switch, 28 is a subscriber circuit, 29 is a subscriber line, and 30 is a central processing unit.

On the exchange side, according to the calling information such as a dial number, if the other side has an eavesdropping prevention device, the exchange side operates so as to connect to the other side without going through the wiretapping prevention decoding device 21 in the exchange. With the eavesdropping prevention device on the side, it is possible to release the confidential talk state and realize the call.

On the other hand, when the other subscriber does not have the wiretapping prevention device, the switch of the exchange is connected to the other terminal via the wiretapping prevention decoding device 21 in the exchange according to the information in the control signal. Control 27. Wiretapping prevention decryption device
In 21, the modem circuit 22 converts an in-band signal into a baseband digital signal, and the voice information is decoded by a randomizing circuit 23 such as bit rearrangement processing on the terminal side.

The voice signal converted from the terminal side into the Psyselp coded signal is converted into the PCM signal normally used in the telephone network by the coded mutual conversion circuit 24 in the next stage,
An analog signal from the subscriber circuit is connected to the partner telephone.

Next, the flow of signals in the opposite direction when the partner terminal does not have the wiretapping prevention device will be described. The voice signal from the partner terminal is sent to the subscriber circuit 28 in the μ-L
It is converted into an AW PCM code and connected to the wiretapping prevention decoding device 21. In this device, after being converted into a Psyselup coded signal by the coding mutual conversion circuit 24, a bit rearrangement process is performed by the randomization circuit 23 according to the same rule as the terminal side, and a modem circuit together with a control signal from the control circuit 25. The signal is converted into an in-band signal by 22 and is guided to the wiretapping prevention device on the terminal side via the switch 27 of the exchange.

In the wiretapping prevention device 11 on the terminal side, the clock / timing extraction circuit 14 extracts the analog modem signal from the received signal.
Then, the required operation clock and the like in the device are extracted and created and distributed to each functional circuit. On the other hand, the signal converted into the baseband signal by the modem circuit 17 is separated into a voice signal and a control signal, and the voice signal is demultiplexed into a Psyselup coded signal through the randomizing circuit 16 and then analogized by the codec circuit 15. It is converted into a voice signal and sent to the telephone terminal.

The control information in the baseband signal is the control circuit
13 is input to and separated into information necessary for controlling the device, such as the conversion rule of the randomizing circuit 16, stored and stored in the memory circuit 12 as needed, and also sent to the circuit and sent to each circuit. Instruct the required action. In this embodiment, the case where 48 Kbps is used as the modem is shown, but FIG. 3 shows an example of information mapping of subscriber line signals of voice signals and control signals.

In the figure, a 48 Kbps subscriber line signal per frame is separated into a control signal of 1.35 Kbps and a voice signal of 3.45 Kbps, and the control signal of 1.35 Kbps is randomized by a signal * 1 indicating whether or not an eavesdropping prevention device is present. It is composed of a signal * 2 for designating a control rule and others, and an error correction code. The signal * 1 indicating the presence or absence of the wiretapping prevention device is set by turning on / off the PB signal from the subscriber on the terminal side, but can also be set by dial information from the other subscriber.

FIG. 4 shows a processing flow of the wiretapping prevention device terminal side of the present invention, and FIG. 5 shows a processing flow of the wiretapping prevention device exchange. In the processing flow on the terminal side of the wiretapping prevention device of FIG. 4, (1) it is checked whether or not the wiretapping prevention function button is turned on on the side of the subscriber terminal, and if not DN, there is no wiretapping prevention function and the process ends. (2) If the wiretapping prevention function button is turned on, the encoding method (here, PSI-SELP method) is selected according to the information from the control unit in the psi self-encoding / decoding circuit,
Converts analog signals to digital signals. (3) The randomizing circuit rearranges the bit strings according to the information from the control unit. (4) In the modem circuit, the control signal is mapped in one frame together with the encoded voice signal by the information from the control unit (this point is different from the conventional one). The control information includes random control rule information and error correction code type information. (5) The modem circuit converts the digital signal into an analog signal and sends the data to the exchange side.

In the processing flow on the side of the wiretapping prevention device switch shown in FIG. 5, (11) it is checked by software control whether or not a call is made from the wiretapping prevention service subscriber based on the calling information, and the wiretapping prevention service subscriber is checked. If the call is not from, the path is set to the other terminal. (12) Eavesdropping prevention service If the call originates from a subscriber, the path is set to the eavesdropping prevention device by software control. (13) In the control circuit of the wiretapping prevention device, the control information is identified and it is checked whether the wiretapping prevention service is turned on. If not, the path is set to the partner terminal by software control. (14) If the wiretapping prevention service is turned on, the wiretapping prevention control information is read, and the random control regulation information, the error correction code identification information, and the like are read. (15) In the randomizing circuit, processing such as rearrangement of bit strings is performed according to information from the control unit. (16) In the encoding mutual conversion circuit, the decoding system is selected according to the information from the control unit, and (here, PSI-SELP
Method) Converted to a PCM signal and sent to the other terminal. (17) Set the bus to the other terminal via the wiretapping prevention device.

[0031]

As a result of implementing the present invention, a telephone subscriber having an eavesdropping prevention device can join his / her own terminal side (telephone-exchange exchange) even if the other party's terminal does not have an eavesdropping prevention device. It is possible to prevent eavesdropping on the person's line).

Also, on the exchange side, the wiretapping prevention decoding device /
Just by adding a function, the wiretapping prevention function on the terminal side can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is an embodiment of a block configuration diagram of an eavesdropping prevention device.

FIG. 3 Example of subscriber line signal information mapping

[FIG. 4] Processing flow on the terminal side of the wiretapping prevention device

FIG. 5: Processing flow on the side of the wiretapping prevention device exchange

FIG. 6 A wiretapping prevention method according to a conventional technique

[Explanation of symbols] 1 Telephone 1,7 Eavesdropping prevention terminal side device 4 Eavesdropping prevention station side device 3,6,8,28 Subscriber circuit 5,27 Exchange switch 2,9,29,37,38,39 Subscriber line 11,34,35 Eavesdropping prevention device (terminal side) 12,26 Memory circuit 13,25 Control circuit 14 Timing extraction circuit 15 Busy Serp code / decoding circuit 16,23 Randomization circuit 17,22 Modem circuit 18, 31, 32, 33 Telephone 19 Subscriber line 20 Switch 21 Eavesdropping decoding device 24 Coding mutual conversion circuit 30 Central processing unit 36 Telephone switching network 40 Bypass

Claims (10)

[Claims] 1. A wiretapping prevention service providing method, comprising: a wiretapping prevention device or a wiretapping prevention function on a terminal side, and a function of canceling and executing a voice signal process for wiretapping prevention on the exchange side. 2. The method of providing a wiretapping prevention service according to the above-mentioned method of providing wiretapping prevention service, by transmitting / receiving the presence / absence information of the wiretapping prevention device / function of the other subscriber between the terminal side device / function and the station side device / function. The method for providing an eavesdropping prevention service according to claim 1, characterized in that the call is passed or not passed through the station side device. 3. The eavesdropping prevention service providing method, wherein the presence / absence information of the eavesdropping prevention device / function of the other subscriber is transmitted and received between the terminal side device / function and the station side device / function, whereby the voice of the station side device is transmitted. The wiretapping prevention service providing method according to claim 1, wherein the signal processing function is operated or stopped. 4. The wiretapping prevention service providing method, wherein the type information of a voice signal processing rule is transmitted and received between a terminal side device / function and a station side device / function to mutually change the voice signal processing rule. The wiretapping prevention service providing method according to claim 1. 5. The eavesdropping prevention service providing method according to claim 1, wherein in the method of providing an eavesdropping prevention service, the communication path of the exchange is set to be through or not through the station side device according to dial information from the subscriber. Method. 6. The eavesdropping prevention service providing method according to claim 1, wherein in the eavesdropping prevention service providing method, the voice signal processing function of the station side device is operated or stopped according to dial information from the subscriber. . 7. The wiretapping prevention service providing method, according to dial information from a partner subscriber, connects to a subscriber equipped with a wiretapping device to activate or deactivate the voice processing function of the station side device. The wiretapping prevention service providing method according to claim 1. 8. The wiretapping prevention service according to claim 1, wherein, in the method of providing the wiretapping prevention service, the call path setting on the exchange side is set to be via or not via the station side device according to dial information from the other party subscriber. Service provision method. 9. The eavesdropping prevention service providing method, wherein the voice processing function of the terminal-side device is activated or deactivated from the exchange side between the terminal-side device / function and the station-side device / function. Item 1. A method for providing wiretapping prevention service according to item 1. 10. The wiretapping prevention service providing method according to claim 1, wherein in the wiretapping prevention service providing method, a trunk side function is provided in a trunk of the trunk line.