KR100318965B1 - System and method for supervising and wiretapping of subscriber in exchange system - Google Patents

Abstract

The present invention provides a method for monitoring and intercepting subscribers in an exchange system having a control system for outputting result data according to the command to a user when a command is input from a user, the monitoring for a specific mobile subscriber from the control system. And when the monitoring request is detected, registering the monitored mobile subscriber to be monitored and monitored, and registering the mobile subscriber as a target for monitoring and interception. And establishing a voice channel with the control system to transmit voice information on the established call, and transmitting the voice information during the call of the generated call to the control system through the set voice channel.

Description

System and Method for Monitoring and Eavesdropping of Subscribers in Exchange System {SYSTEM AND METHOD FOR SUPERVISING AND WIRETAPPING OF SUBSCRIBER IN EXCHANGE SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cellular mobile telecommunication system, and in particular, to monitor and supervise a particular subscriber's call in an exchange system. A system and method for the same.

The cellular mobile communication system divides the entire service area into a plurality of base station areas and constitutes cells, which are small service areas, and centrally controls these base stations with a switching system, thereby allowing subscribers to move between cells. To continue.

1 shows a schematic diagram of a typical cellular mobile communication network, applicable to all kinds of wireless systems using Code Division Multiple Access (CDMA) technology, as shown. A mobile station (MS) 10 providing a mobile communication service to the mobile station, a base station (BS) 20 connected to the mobile terminal 10 through a wireless link, the base station 20 and the public Connected to a Publish Switched Telephone Network (PSTN) 50, the subscriber's information is retrieved from a Home Location Register (HLR) 40 and transferred to the mobile subscriber through the base station 20. It consists of an Exchange System 30 that provides communication services.

As shown in FIG. 1, under the control of an Access Switched Processor (ASP), a plurality of Access Switched Subsystems that are matched with other systems (base stations, HLR, PSTN, other switching systems, etc.) A path between the plurality of access exchange subsystems 31, 32, 33, under the control of an ASS 31, 32, 33, and an Interconnection Network Processor (INP). Central control for controlling the switching operation of the interconnect network subsystem 70 by control of a switching interconnect network subsystem (INS) 70 and an operation and maintenance processor (OMP). It consists of a Central Control Subsystem (CCS) 80.

The ASS-M (mobile) 31 matches with the base station 20 to handle the call processing of the subscriber, and the ASS-7 (ASS-signaling system no. 7) 32 is connected to another switching station (Mobile) by SS7. eXchange: MX) and Home Locator (HLR) or other exchange systems, ASS-T (trunk) 33 is connected to the PSTN and other exchange systems. In addition, ASS-S / T (subscriber and trunk) has the function of the ASS-T (33) to match the fixed telephone and to handle the call processing by the fixed telephone.

In a cellular mobile communication network configured as above, the operator of the network may be required to monitor and intercept a particular mobile subscriber. For example, if the police or the government needs the call data of a particular mobile subscriber for legitimate warrants, the exchange system sends the voice information transmitted and received by the mobile subscriber to another subscriber by the police or the government. It needs to be sent to an authorized legitimate system.

However, the conventional exchange system operating as described above transmits voice information transmitted and received by the mobile subscriber to another control point (CP) to the other subscriber for the purpose of monitoring and listening to a specific mobile subscriber. The problem is that they do not have the means to do so.

Accordingly, an object of the present invention, which is invented to solve the problems of the prior art operated as described above, is to monitor / tap the specific mobile subscribers (the System of technical facilities for realizing the Operative Search Measures: SOSM). A host protocol control (HPC) block that controls the X.25 protocol between the block and the exchange system and an external control point (CP) is implemented in different subsystems within the exchange system. The present invention provides a system and method for monitoring / sensing a subscriber in a switching system that transmits voice information transmitted and received by another mobile subscriber to another subscriber through a relay line to the control system (CP).

1 is a block diagram of a typical cellular mobile communication system and a switching system.

Figure 2 is an embodiment of the monitoring / monitoring system configuration according to the present invention.

3 is a block diagram illustrating a connection for operation of an SOSM block according to the present invention;

Figure 4 is a flow chart showing an embodiment of the monitoring / monitoring method according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: mobile terminal (MS) 20: base station (BS)

30: exchange system 40: home position register (HLR)

50: Public Switched Telephone Network (PSTN)

31,32,33,200: Access Switching Subsystem (ASS)

34,100: interconnect network subsystem (INS)

35: central control subsystem (CCS) 110: monitoring / monitoring (SOSM) block

120: RCO 130: MCC

140: TCR 150: TC7

160: TDMH

210: host protocol control block (HPC)

220: modem / DSU 230: relay line matching device

300: control system

According to the present invention, when monitoring and eavesdropping of a specific mobile subscriber is required through a legitimate procedure, a user requests the switching system to monitor / hear the mobile subscriber using a control point (CP).

The system of technical facilities for realizing the Operative Search Measures (SOSM), which monitors / hears at the command of the control system in the switching system, the monitoring and eavesdropping commands for specific mobile subscribers from the control system. When is received, it responds to it and then transfers the interrogated voice information to the control system by connecting the call of the mobile subscriber to be monitored / monitored to the control system.

Since the switching system and the control system are connected by an X.25 protocol, the switching system has a Host Protocol Control (HPC) block that controls the X.25 protocol. The HPC block controls the state of the X.25 protocol and X.25 ports between the switching system and the control system, and performs interconversion between packets for IPC and packets for X.25 communication within the switching system.

According to the present invention, the SOSM block performing the monitoring / auditing function in the switching system is purely dedicated to the control of voice information and data, and the HPC block is responsible for controlling the protocol and port control related to X.25. The two blocks are implemented in different subsystems within the switching system, so that the two blocks are functionally separated from each other.

In an exchange system composed of an access exchange subsystem (ASS), an interconnect network subsystem (INS), and a central control subsystem (CCS) as shown in FIG. 1, the SOSM block according to the present invention is characterized in that the interconnect network subsystem ( INS is implemented in an Interconnection Network Processor (INP), and the HPC block according to the present invention is implemented in an Access Switching Processor (ASP) that controls the access exchange subsystem (ASS). do.

The call processing function, which is the most important function of the exchange system, is performed by an Operation and Maintenance Subsystem (OMP) that controls the Central Control Subsystem (CCS). The present invention manages the SOSM block and the HPC block. By separating from the subsystem (OMP), the operation of the SOSM block and the HPC block is independent of the operation of the operations management subsystem (OMP). Thus, for example, even if the operations management subsystem (OMP) becomes overloaded during call processing, the SOSM block and the HPC block can normally perform monitoring / hearing operations.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention.

FIG. 2 illustrates an embodiment of a surveillance / hearing system configuration in accordance with the present invention, and, as shown, within the interconnection network processor (INP) 100 of a switching system, monitoring and listening instructions for a particular mobile subscriber. A monitoring / sensing (SOSM) block 110 for monitoring and intercepting voice information of the mobile subscriber when a call of the mobile subscriber occurs; A host protocol control (HPC) block 210 coupled to the SOSM block via an interprocessor communication (IPC) within an access exchange subsystem (200) and controlling an X.25 protocol; And a control system 300 connected to the HPC block 210 through a data channel and to the SOSM block 110 through a voice channel, and controlling a monitoring / sensing function of the SOSM block 110 by a user. It includes.

The exchange system 400 is connected to the control system 300 through the relay line matching device 230 and the modem / DSU (DSU) 220.

The switching system 400 is connected to the control system 300 via a data channel and a voice channel, and the data channel is in a direction opposite to a command transmitted from the control system 300 to the switching system 400. The voice channel carries the transmitted response, and the voice channel carries the voice information intercepted by the switching system 400 to the control system 300 by the command.

The voice channel may be implemented as a relay line connecting the switching system 400 and the control system 300. The data channel may be shared with the relay line or implemented as a separate dedicated line.

That is, the data channel may be a Pulse Code Modulation (PCM) link by a digital service device (DSU) that satisfies V.35 as recommended by the International Telegraph and Telephone Consultative CommITTee (CCITT), or as recommended by the CCITT. It can be implemented with a dedicated line such as a modem link that satisfies V.24. The user connects the control system 300 to the switching system 400 through a PCM link / modem link, which is a dedicated line, or a relay line, which is a common line, as necessary.

In the monitoring / monitoring system according to the present invention, the SOSM block 110 resides in the INP 100 of the INS, and the HPC block 210 resides in the ASS 200. The SOSM block 110 and the HPC block 210 are connected through inter-processor communication (IPC).

The HPC block 210 is connected to the control system 300 via a plurality of modem links (or PCM links) and a plurality of relay lines 230, for example, the HPC block 210 is connected to eight modem links (or PCM links). Link) and four relay lines. Since the modem link (or PCM link) and the relay line follow the protocol according to X.25, the HPC block 210 controls the X.25 protocol so that the SOSM block 110 can communicate with the control system 300. .

The SOSM block 110 is dedicated to the function of monitoring / monitoring by the command of the control system 300, and the HPC block 210 is in charge of controlling the X.25 related protocol and controlling the data channel.

Since the functions of the two blocks are independent as described above, the HPC block 210 may exist in any subsystem of the ASS_T type (ASS_T or ASS_S / T) capable of controlling the relay line. Thus, no matter what ASS the HPC block 210 resides in, the SOSM block 110 can interwork with the HPC block 210 by searching for the ASS_T type subsystem by searching for the type of ASP that is the processor of the ASS. . This is because the type of ASS is determined by the type of ASP.

In addition, among the commands transmitted by the control system 300, the function that the SOSM block 110 does not need to be performed by the HPC block 210 itself, thereby saving the response time of the command, SOSM It reduces the load of the intermatching network processor (INP) generated by the operation of the block 110 or the IPC usage between the SOSM block 110 and the HPC block 210.

When the user inputs the information of the mobile subscriber to be monitored / monitored by the control system 300, the control system 300 transmits a monitoring / monitoring command to the HPC block 210 through the data channel according to X.25. do. At this time, the user inputs the relay line number of the data channel connected to the ASS including the HPC block 210 to select the ASS to which the control system 300 is connected.

The HPC block 210 receiving the monitoring / monitoring command converts the monitoring / monitoring command of the packet format according to the X.25 protocol into the packet form of the IPC, and then the monitoring / monitoring command converted to the IPC format. To the SOSM block 110 via IPC.

The SOSM block 110 manages the information of the mobile subscribers set as the targets of monitoring / monitoring by the control system 300 in a database. When a call event of a mobile subscriber occurs, the switching system 400 allocates a call processing block to each subscriber who is conducting a call, and the call processing block performs communication service for one subscriber.

Therefore, when a call event of a mobile subscriber to be monitored / listened is stored in the database, the SOSM block 110 receives subscriber information for monitoring / hearing from the call processing block assigned to the mobile subscriber, and the control system 300. Connect the audio channel for monitoring, i.e., the Monitoring Connection Line (MCL).

When the call setup is completed by the call processing block and the monitoring / monitoring subscriber starts the call, the voice information of the monitoring / monitoring subscriber is received to the control system 300 through the voice channel, and the control system 300 The received voice information is translated and provided to the user.

The control system 300 can obtain information from the SOSM block 110, for example, to which subscriber the monitored / monitored subscriber requests outgoing call, from which subscriber the incoming call is requested, how long the call is currently in progress, and the like. have.

If the switching system is restarted or the operation and maintenance processor (OMP) of the switching system is restarted, the SOSM block 110 sends the restart information to the control system 300. Control system 300 then requests initialization to SOSM block 110, such that SOSM block 110 is initialized.

As described above, the control system 300 transmits instructions for monitoring / sensing to the SOSM block 110 through the data channel, and thus the SOSM block 110 receives from the control system 300. Perform an operation according to one command. Here, the operation functions performed by the SOSM block 110 for monitoring / monitoring are as follows.

1. Initial Drive and Stop / Pause: The control system 300 monitors / taps the requested specific mobile subscriber to the SOSM block 110 as a user is requested to monitor / hear for a specific mobile subscriber. Command the start of operation, and the SOSM block 110 performs the initial drive according to the start operation command of the control system 300. As described above, when the exchange system is restarted or the operation management processor (OMP) of the exchange system is restarted, the SOSM block 110 transmits restart information to the control system 300. Then, the control system 300 that has received the restart information requests initialization to the SOSM block 110, and the SOSM block 110 performs initial driving. The SOSM block 110 performs an operation of stopping / pausing its own operation.

2. Establishment and release of mobile subscribers to be monitored / monitored: The SOSM block 110 receives a monitoring / sensing request for a specific mobile subscriber from the control system 300 to be the target of the monitoring / auditing request. The mobile subscriber's information is registered in the SOSM block 110 own database and set as a monitoring / taking target. On the contrary, upon receiving the monitoring / auditing release request for a specific mobile subscriber from the control system 300, the SOSM block 110 deletes the information of the mobile subscriber who is the target of the monitoring / auditing release request from the database. Cancel the setting of the monitoring / auditing target.

3. Establishment and release of voice channel for monitoring / hearing: When the SOSM block 110 receives a monitoring / hearing request for a specific mobile subscriber from the control system 300, the SOSM block 110 generates a call for the specific mobile subscriber. Set up a voice channel to monitor / listen voice information for a call. On the contrary, the set voice channel is canceled according to the call termination during the monitoring / monitoring.

4. Acquisition and Transmission of Data (Voice Information) According to Surveillance / Eavesdropping: As described above, while the voice channel for monitoring / hearing is connected to a specific mobile subscriber, the SOSM block 110 displays the call contents of the mobile subscriber. Collect the data according to the (voice information), and transmit the collected data through the voice channel.

5. Transmission of Information on Voice Channel: The SOSM block 110 sets up a voice channel to be monitored / listened for a specific mobile subscriber. Accordingly, the SOSM block 110 sets information on the set voice channel, for example. Voice channel information such as a call number of the call to be monitored / listened or the location information of the mobile subscriber is transmitted to the control system 300.

6. Stopping and resuming monitoring / auditing data transmission: The SOSM block 110 stops transmitting the monitoring / auditing data, ie, voice information, which was being transmitted through the voice channel according to the command of the control system 300, In addition, according to the command of the control system 300 resumes the monitoring / monitoring data transmission that has been suspended.

The voice channel between the control system 300 and the SOSM block 110 is composed of a relay line. The number of relay lines for the voice channel is set by the user according to the capacity of the voice to be monitored / monitored regardless of the capacity of the switching system. Can be. That is, the user selects the number of relay lines to be used for the voice channel through the control system 300.

According to ITU-T G.732, the trunk lines for the voice channel each have a speed of 64 kbps and consist of 32 time slots capable of transmitting packets according to X.25. In each of the relay lines, timeslots 1 to 15 and timeslots 17 to 29 are used for transmission of voice information to be monitored / listened, and timeslot 16 is not used by the control system 300.

The data channel between the control system 300 and the HPC block 210 is composed of eight modem links (or PCM links) or four relay lines, and the control system is a modem link (or PCM link) depending on the purpose of monitoring / monitoring. Or select the relay line.

Each relay line used as a data channel is composed of 32 timeslots, and 0 to 29 timeslots are Don't care and are not used for monitoring / tapping. The timeslots 30 and 31 of the first and second relay lines, which are the first relay line combinations, transmit a command and a response for monitoring / tapping.

The third and fourth relay lines, which are combinations of the second relay lines, are reserved in case of failure of the first and second relay lines, an overload condition or a failure of the voice channel. At each relay line, timeslot 30 is used for sending commands for monitoring / hearing and timeslot 31 is used for sending a response to the commands.

3 is a diagram illustrating a connection for operation of an SOSM block according to the present invention. As shown, the SOSM block 110 includes a route control (RCO) block 120, a mobile call control (MCC) block 130, a trunk call control (TCR) block 140, and a TC7 (Trunk) of a switching system. Call Control for Signaling System no.7) obtains information on the call progress of the subscriber to be monitored / monitored from the block 150, the telephony device maintenance (TDMH) 160, and the HLR 40, and performs the voice of the subscriber to be monitored / monitored. Collect information.

The SOSM block 110 uses the information received from the RCO block 120, the MCC block 130, the TCR block 140, and the TC7 block 150 to determine the subscriber to be monitored / monitored, and the subscriber to be monitored / monitored. When a call event occurs, the voice channel is assigned to the subscriber to perform the monitoring / listening function and manage the monitoring / listening connection information of the call in progress.

The SOSM block 110 obtains the information of the subscriber to be monitored / listened from the HLR 40 and receives a report on the status of the voice channel for monitoring / listening from the TDMH block 160.

4 is a flowchart illustrating a method for monitoring / sensing a mobile subscriber according to the present invention, as shown in FIG. 4, in which a user requests monitoring and interception of a specific mobile subscriber from a switching system through a control system; ; In response to the request, the switching system responding to the control system and registering the mobile subscriber as an object of monitoring and monitoring (s120); Requesting call setup of the mobile subscriber to the switching system (s130); Confirming whether the mobile subscriber is registered as an object of monitoring and interception (s140); If it is not registered as a result of the checking, connecting the call of the mobile subscriber and providing a normal call service (s150); And if the check result is registered, connecting the call of the mobile subscriber and providing a normal call service, and intercepting and transmitting the voice information of the mobile subscriber to the control system (s160).

Referring to the drawings, the operation of the monitoring / monitoring system according to the present invention will be described in detail as follows.

When the user requests the control system 300 to monitor / listen for a particular mobile subscriber, the SOSM block 110 registers the mobile subscriber as a target of monitoring / monitoring in the database by a command of the control system. In the database, all mobile subscribers who are monitored / supervised by the control system 300 are registered.

When a mobile subscriber makes a call to the switching system through a base station, the switching system translates the calling mobile subscriber's number and retrieves the information of the calling mobile subscriber using the translated number. As a result of retrieving the information of the outgoing mobile subscriber, if the outgoing mobile subscriber is registered in the database of the SOSM for monitoring / monitoring, the SOSM block 110 assigns a call number (No. of Call) to the outgoing mobile subscriber, Allocate voice channel for monitoring / monitoring outgoing mobile subscriber.

The switching system requests the home location register (HLR) 40 to retrieve the location of the called subscriber, and the home location register retrieves the location of the called subscriber and, as a result, responds to the switching system with information of the called mobile subscriber.

The switching system uses the information of the called mobile subscriber to confirm that the called mobile subscriber is registered with the SOSM for monitoring / monitoring. If the incoming mobile subscriber is the subject of monitoring / listening, the SOSM block assigns a call number to the incoming mobile subscriber and allocates a voice channel for monitoring / listening of the incoming mobile subscriber.

The voice channel is for transmitting voice information of the originating or mobile subscriber to the control system.

The switching system finds the base station where the called mobile subscriber is located from the information of the called mobile subscriber and calls the called mobile subscriber through the base station. When the called mobile subscriber answers the call, the switching system connects the call path between the calling mobile subscriber and the called mobile subscriber through switching.

When the call path between the originating mobile subscriber and the called mobile subscriber is connected, the call processing block of the originating mobile subscriber (ie, the originating call processing block) informs the call processing block (that is, the incoming call processing block) of the called mobile subscriber about the voice channel. send.

The originating call processing block then connects the voice channel allocated for monitoring / monitoring the originating mobile subscriber and reports it to the SOSM block, and the incoming call processing block likewise assigns the voice allocated for the monitoring / hearing of the incoming mobile subscriber. Connect the channel and report it to the SOSM block. When it is reported that the voice channel of the originating and terminating mobile subscriber is connected, the SOSM block informs the control system that the originating and terminating mobile subscriber has answered.

Then, when the originating call processing block and the incoming call processing block initiate a call, the SOSM block controls voice information transmitted and received between the originating and incoming mobile subscribers through the originating and incoming call processing blocks through the voice channel for each mobile subscriber. Pass each to the system.

If the control system requests the release of the voice channel for monitoring / monitoring a specific mobile subscriber while performing the monitoring / auditing process as described above, the call processing block of the mobile subscriber is sent to the monitoring / hearing. Release the assigned voice channel and report it to the SOSM block.

In addition, when the originating mobile subscriber and the terminating mobile subscriber terminate the call normally and release the connection, the call processing block of the originating and incoming mobile subscriber releases the voice channel allocated for monitoring / hearing and reports it to the SOSM block. .

When the voice channel allocated for monitoring / listening is released, the SOSM block reports it to the control system and ends the monitoring / listening operation.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

In the present invention, the SOSM block is purely dedicated to the monitoring / monitoring function, and the protocol control function and the port control function related to X.25 are performed by the HPC block, so that the two blocks can be functionally separated from each other. Therefore, the ASS connected to the control system is not fixed, and the ASS can be variably selected according to the setting of the relay line input by the user.

In addition, the monitoring / auditing system according to the present invention does not affect the original function of the switching system at all, and since the switching system does not provide any information to the control system, it is possible to perform the monitoring / monitoring function in which complete security is maintained. have.

Claims (18)

A plurality of Access Switched Subsystems (ASSs) that are matched with mobile communication base stations and other systems under the control of an Access Switched Processor (ASP), and an Interconnection Network Processor (INP). An interconnection network subsystem (INS) for switching paths between the plurality of access exchange subsystems under control of the interconnection network and an interconnection network under the control of an operation and maintenance processor (OMP). A system for monitoring and interception of subscribers in an exchange system having a Central Control Subsystem (CCS) that controls the switching operation of the subsystem, Detects a monitoring and interception request for a specific mobile subscriber from a user, instructs monitoring and interception of the specific mobile subscriber according to the monitoring and interception request, and sends the audio information intercepted by the monitoring and interception command to the user A control system for outputting; And mounted in the mutual matching network processor (INP) to form a data channel with the control system to receive commands related to the monitoring and listening, to send a response to the received command, and to transmit the control system and the voice channel. A monitoring / monitoring (SOSM) block for forming and transmitting voice information of the mobile subscriber requested to be monitored and intercepted to the control system; Host Protocol Control (HPC), which is mounted in the access exchange processor (ASP), communicates with the SOSM block via interprocessor communication (IPC), and controls an X.25 protocol between the control system and the exchange system. System) block. The method of claim 1, wherein the SOSM block, And detecting an ASS having the HPC block by searching each processor type of the plurality of ASSs, and forming a data channel with the detected ASS to perform a communication connection. The method of claim 2, wherein the ASS having the HPC block, And an ASS_T (trunk) type that connects the exchange system with the relay line. The method of claim 3, wherein the SOSM block, And a database for storing mobile subscriber information as a monitoring / taping target that receives the monitoring and interception commands from the control system. The method of claim 4, wherein the SOSM block, And when a call origination is detected for the mobile subscriber registered as the monitoring / auditing target, collecting voice information of the mobile subscriber and transmitting the voice information through the voice channel. The method of claim 5, wherein the SOSM block, And a voice channel is set according to the call occurrence, and the voice channel setting is released when the call ends after the voice channel is set. The method of claim 6, wherein the SOSM block, And if the exchange system is restarted or the operation management processor of the exchange system is restarted, restart information according to the restart is transmitted to the control system. The method of claim 1, wherein the voice channel, A system comprising a plurality of relay lines each having 32 timeslots, wherein voice information is transmitted through timeslots 1 to 15 and timeslots 17 to 29 of each relay line. The method of claim 8, wherein the voice channel, And variably adjusting the number of relay lines used according to the size of voice information used for monitoring and interception. The method of claim 1, wherein the HPC block, And determining whether the SOSM block needs to execute the command with respect to the command of the control system, and if the SOSM block does not need to execute the command, the HPC block processes itself. The method of claim 10, wherein the HPC block, Converts an X.25 type packet transmitted from the control system through the data channel into an IPC type packet and transmits the packet to the SOSM block, And converts an IPC packet transmitted from the SOSM block into an X.25 packet and delivers the packet to the control system through the IPC. The method of claim 11, wherein the data channel, And at least one modem link or at least one pulse code modulation (PCM) link or at least one relay line. The method of claim 12, wherein the relay line, And a first relay line combination used to transmit a command and a response between the HPC block and the control system, and a second relay line combination which is a preliminary relay line for the first relay line combination. The method of claim 13, wherein the relay line, 32 timeslots each, timeslot 30 sending a command sent from the control system and timeslot 31 sending a response to the command. The method of claim 14, wherein the control system, And ASS connected to one of the ASSs according to the user's setting. The method of claim 1, wherein the control system, Translate the voice information received from the SOSM block and output it to the user; And requesting initialization from the SOSM block when information on restart is received from the SOSM block. The method of claim 16, wherein the control system, If the user detects a monitoring / auditing release request for a mobile subscriber who is already registered as a monitoring / auditing target, the SOSM block is configured to release the monitoring / auditing target registration for the released mobile subscriber; system. A method for monitoring and intercepting subscribers in an exchange system having a control system for outputting result data according to the command to a user upon receiving a command from a user, Registering the mobile subscriber who is requested to be monitored and intercepted as an object of monitoring and interception when a monitoring and interception request for a specific mobile subscriber is detected from the control system; Setting up a voice channel with the control system to transmit voice information about the generated call when a call origination is detected for the mobile subscriber after registering the mobile subscriber as a monitoring and listening target; Transmitting voice information of the generated call to the control system through the set voice channel.