JPS59122039A - Secret communication control system - Google Patents

Abstract

PURPOSE:To utilize a secret service function effectively for secret communication by making a normal local connection for mutual connection between secret terminals, and making the connection to a local trunk where a secret device is connected when only one terminal has the secret service function. CONSTITUTION:A voice signal from a terminal E having the secret service function is modulated by the secret device SC6 into a secret voice signal, which is sent out to the opposite secret device SC7 through the link L4 of the network NW2 of a switchboard and the link L5 of the local trunk IOT2. This device SC7 demodulates and sends the secret voice signal to a terminal F. When communicating with a terminal G which has not the secret service function, the local trunk IOT2 controls a switching circuit CONN to connect the local trunk IOT2 to a secret device SC8. Then, a voice signal passed by the device SC8 is modulated into a secret signal or demodulated reversely and sent to the links L4 and L6 to offer the secret service.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to an exchange that connects a terminal line with a secure function and a telephone terminal line without a secure function. This invention relates to a secret call control system for making secret call connections.

(2) Background of the technology In recent years, damage such as wiretapping of telephone calls in the middle of communication lines, data being extracted from the middle of online private lines of banks, etc., and encryption codes being decoded has been occurring frequently, and this has become a social problem. For this purpose, various concealment devices have been developed and put into practical use, but the reality is that they are costly and have not yet become widespread.

(3) Prior Art and Problems FIG. 1 shows a conventional secret call system. When subscriber A, who has a concealment function, makes a call to called party B, the voice signal of subscriber A is modulated by a concealment signal by the concealment device SCO, and sent to the concealment device SC as a concealment voice signal.
The 0 secrecy device SC1 sent to I demodulates the secrecy audio signal into an audio signal and sends it to the called party B via the network NWO - link Ll - intra-office trunk IoTo - link L2. On the other hand, the voice signal of caller B is
The CI sends it as a secret audio signal to the secret device SCo. The secret device SCO demodulates the voice (N code) and sends it to the calling party A, and performs intra-office mutual communication between subscribers A and B.

Figure 2 shows the connections between the secret lines.

The voice signal of the secret subscriber C is modulated into a secret voice signal by the secret device SC2 and sent to the secret device SC3. The secret device SC3 demodulates the voice signal and sends it to the secret device SC5 through the link L2 of the network NWI - the intra-office trunk uT1 - the link L3.

The secret device SC5 modulates the secret audio signal again and sends it to the secret device SC4. The secret device SC4 demodulates the voice signal again and sends it to the called party. The voice signal of the called party undergoes the reverse variable demodulation described above and is sent to the calling party C'. In this connection, since the secret signal is modulated and demodulated twice each, the signal quality of the call is extremely poor, making the call between the secret subscribers unusable.

(4) Purpose of the Invention An object of the present invention is to enable anonymous calls between terminals with a security function, and to effectively use the security function in an exchange to which a terminal with a security function and a terminal without a security function are connected. An object of the present invention is to provide a secret call control method for conducting secret calls using a private phone.

(5) Structure of the Invention In a telephone exchange that accommodates terminals of the same class that have a secure call function, the secure line is connected between the terminals using a normal own-station connection, and only one of the line terminals has the secure call function. In the case of a connection in which a trunk within the own office is connected to a secret device and a secret call connection is made, a secret call control method is used, or a tNLN intercom that houses a line terminal with a call function in the secret picture is used to perform a secret call control method. If the connection is between terminals, use a normal outgoing connection from your own station, but if only one of the terminals has a secure call function, connect to the trunk within your own station that is directly connected to the concealed device to establish a secure call connection. : This is achieved by providing a secret call control method that provides 100% security.

(6) Examples of the invention An embodiment of the present invention is shown in FIG. 3 and will be described in detail.

The present invention takes into consideration the fact that the variable rear leg of the symbol 〇 is performed only once by the concealing device in the connection of LP between terminals having a concealing function, and furthermore, the
The present invention also provides a secure communication connection between a terminal with a security function and a terminal without a security function, making use of the security function as much as possible. The voice signal of the terminal E having the concealment function is modulated into a concealed voice signal by the concealment device SC6 and is sent to the link L4-IiAT2-link L of the network 1''JW2.
5 is made red and white and sent to the secret device SC7. The secret device SC7 demodulates the secret audio signal into an audio signal and sends it to the terminal F.The audio from the terminal F is sent to the terminal E through the above route in reverse. When terminal E makes a call to terminal G that does not have a security function, it controls the switching circuit C0NN to connect the internal trunk L0T2 and the security device SC8, and modulates the confidential signal when passing through the internal trunk. Do the hind legs. The fourth figure is a concrete block diagram of the secret call control method according to the present invention.Relay S operates when a secret terminal and a general extension line communicate, and the call is made via the secret device. Relay C is a relay that operates when calling a secret terminal from a general extension line and making a call. Since a call from a secret terminal to a secret terminal is passed through the trunk within the own office as a secret voice signal, the connection relay S to the secret device is not operated. For a call from a hidden terminal to a regular telephone, only the s relay is activated and the calling party's hidden terminal is connected to the hidden voice signal side of the concealed device.The called party's regular telephone is connected to the voice signal side of the concealed device. Connecting. When making a call from a general telephone to a secret terminal, the s relay and c relay are activated, and each is connected to the signal side of the corresponding secret device. FIG. 5 shows another embodiment of the invention. In this example, only some of the trunks within the local office are equipped with a concealment device. When connecting within the local office, it is possible to identify whether the call is between a hidden terminal and a regular telephone based on the subscriber class of the caller or the called party. Therefore, the present invention'f1: No new technology is required to implement the invention.The exchange FA identifies whether the connection is from a hidden terminal to a general @phone, or from a general talk 4μ to a hidden terminal, and automatically To connect the in-office trunk calling and called ports to each terminal and the corresponding signaling system, use S mentioned above.

C/ Relay control becomes uneasy.

(7) Effects of the Invention According to the present invention, it is not only possible to make calls between two secret lines, but it is also possible to install a secret device that responds to the traffic of secret calls, which is extremely economical. The effect of being able to construct a secret call system is great.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional secret call system, FIG. 2 is another block diagram of the conventional secret call system, FIG. 3 is a block diagram of an embodiment of the secure call system according to the present invention, and FIG. 4 is a block diagram of a conventional secret call system. FIG. 3 is a specific configuration diagram, and FIG. 5 is another configuration diagram of the secure communication system of the present invention. In the drawing, SCO to 5C11 are hidden devices, A to J are subscribers (terminals), NWO to NW3 are networks, L1 to LIO are connection links, and l0TO to l0T4.
indicates the trunk within the local station.

Claims (2)

[Claims] (1) In the case of a connection with a line with a secret call function that accommodates a terminal with a secret call function, it is transcribed within the own station. A secret call control method characterized in that a secret call is connected to a secret device to establish a secret call connection. (2) In a telephone switchboard that accommodates line terminals with a secure call function, if the connection is between two confidential line terminals, a normal internal connection is performed, and if only one of the line terminals has a secure call function, the connection is confidential. A secret call control method characterized by connecting to a trunk within the own office that is directly connected to the device and performing a secret call connection.