JP4148629B2 - Forced line connection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a forced line connection device, and more particularly to a device for forcibly establishing a connection with an emergency terminal such as a security terminal even when all B channels of a subscriber line of an ISDN line are in use.
[0002]
[Prior art]
Conventionally, there has been a security device that detects the occurrence of an emergency such as a fire or an abnormal situation such as an intruder and reports the emergency or abnormal situation (hereinafter collectively referred to as an emergency) to the monitoring center via the ISDN line. It has been put into practical use. When such a security device detects an emergency situation, it automatically sends a call setup message to the monitoring center, and transmits the detected emergency information to the monitoring center after establishing a connection with the monitoring center. To do.
[0003]
However, when the security device detects an emergency situation, if the ISDN subscriber line is already in use, a call setup message may be transmitted to the monitoring center to establish communication with the monitoring center. If it is not possible to wait until the line becomes available, there is a problem that the emergency situation cannot be quickly dealt with. Since the ISDN basic interface includes two B channels for transmitting communication information, it is possible to use two terminals simultaneously on one subscriber line. Therefore, although it is generally considered that both B channels are in use at the same time, the number of terminals connected to ISDN lines such as telephones, facsimiles, personal computers, etc. is increasing. There is a possibility that all the B channels are in use at the same time.
[0004]
FIG. 3 illustrates one method for establishing communication with a monitoring center when a security terminal detects an emergency when all two B channels are in use on an ISDN subscriber line. It is shown.
[0005]
In the figure, a monitoring center 10 is connected to a DSU 14 installed in a user's home via an ISDN exchange 12. A security terminal, a telephone, and a facsimile are connected to the home bus extending from the DSU 14 via the relay 16a in the line disconnection device 16. When the security terminal detects an emergency while using the two B channels (B1 and B2) while the telephone and facsimile are using the line, the line disconnecting device 16 relays the emergency signal from the security terminal as a trigger. 16a is operated to forcibly disconnect the S / T point of the home bus (layer 1 level disconnection). After that, another call is made from the security terminal to establish communication with the monitoring center.
[0006]
[Problems to be solved by the invention]
However, in the above prior art, since all the lines are forcibly disconnected, there is a problem that all the terminals in use become unusable, and the security terminal after disconnection uses one B channel. While communicating with the monitoring center, the other B channel and D channel cannot be used, and there is a problem that the usage efficiency of the ISDN line is lowered.
[0007]
In view of such problems, the applicant of the present application previously proposed the following forced line connection device in Japanese Patent Application No. 10-311179. In other words, a forced line connection device is provided between the ISDN switch and the home DSU, and the RR monitoring frame transmitted / received between the home terminal and the switch is interrupted and any B channel is logically operated at the layer 2 level. release. Also, a disconnection (DISC) message (layer 3 level) is put on the information transfer frame to release communication between the home terminal and the ISDN exchange. As a result, it is possible to prevent other terminals from being affected as in the case of physical disconnection.
[0008]
However, for example, when logical release is performed by blocking RR at the layer 2 level, the ISDN switch automatically takes procedures such as link re-establishment at layer 2 and a predetermined time has passed without being re-established. From the point of view of establishing a communication between the emergency terminal and the monitoring center quickly, a certain time (about 120 sec) is required until communication with the emergency terminal becomes possible. There was a problem that was not always sufficient.
[0009]
In addition, even when terminating at the layer 3 level and the forced line connection device impersonates an ISDN line or a home terminal for disconnection processing, it is necessary to monitor and process all the communication procedures (status) of the home terminal. There was a problem that was not sufficient from the viewpoint of simplification. This manages all communication procedures such as outgoing and disconnected for each communication call of the home terminal, and at the time of disconnection, a disconnection (DISC) message in which the TEI value, channel number, sequence number, etc. of the communication call are set. This is because it is necessary to perform processing for transmitting such information to an ISDN exchange or a home terminal.
[0010]
The present invention has been made in view of the above-described problems of the prior art, and its object is to provide a simple configuration when an emergency situation is detected by an emergency terminal while all B channels of ISDN subscriber lines are in use. It is an object of the present invention to provide a compulsory line connection apparatus that can release a call during communication and can quickly establish communication between an emergency terminal and a monitoring center.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a forced line connection device that releases communication between a home terminal connected to a home DSU and an ISDN switch and establishes communication with an emergency terminal. Line connection means connected to the in-house DSU, the line connection means using means for storing a TEI value in communication between the in-home terminal and the ISDN switch, and using the TEI value Means for transmitting a SABME signal and a RESTART signal to the ISDN switch. By using the TEI value during communication, the line connection means can behave as if it is a home terminal that is communicating, and the SABME signal and the RESTART signal are sent to the ISDN switch as if it is data from the home terminal. Send. As a result, the channel in communication can be released quickly. In addition,
The data link layer entity sets the transmission state variable V (S), the confirmation state variable V (A), and the reception state variable V (R) to 0 by the SABME signal, so that the sequence number in the subsequently transmitted RESTART signal is Even in this case, the initial value can be set. The ISDN exchange that has received the RESTART signal immediately releases the channel, so that it does not take a certain period of time unlike a release due to time-out.
[0012]
Here, the means for storing stores the call number or channel identifier of the B channel used in the TEI value together with the TEI value, and the means for transmitting transmits the TEI value and the call number or channel identifier. It is preferable that the RESTART signal is transmitted. This makes it possible to release only communication with a specific terminal specified by a call number or channel identifier, and establish communication with an emergency terminal by releasing a channel without affecting other terminals. Can do.
[0013]
The line connection unit may include a relay unit that physically cuts off the connection between the home terminal and the ISDN exchange. Thereby, communication with the home terminal can be disconnected. After disconnecting by the relay means and releasing the channel by the SABME and RESTART signals to establish communication with the emergency terminal, the relay means is operated to ensure the physical connection between the home terminal and the ISDN switch. Is desirable. This is to enable reconnection with the home terminal.
[0014]
The line connection means preferably has means for blocking a frame signal of SAPI = 0 transmitted / received between the home terminal and the ISDN exchange, instead of the relay means. Since the relay means physically disconnects, all frame signals from the in-home terminal are blocked, and the communication of the in-home terminal cannot be relieved. However, D channel communication is performed by logically blocking only all SAPI = 0 frame signals and transmitting the SABME signal and the RESTART signal including the TEI value of the blocked frame signal while maintaining the physical connection. All B channel communications can be released while maintaining the above. Further, while maintaining the physical connection, only the frame signal of SAPI = 0 including the specific call number information is logically cut off, and the SABME signal including the TEI value and channel identifier used in the frame signal, and By transmitting the RESTART signal, it is possible to release only a specific 1B channel while maintaining D channel communication and other B channel communication.
[0015]
The line connection means includes a relay means for physically disconnecting the connection between the home terminal and the ISDN switch, and a SAPI = 0 frame signal transmitted / received between the home terminal and the ISDN switch. It is preferable to have a means for shutting off, and a means for alternatively operating either the relay means or the shutting means. This makes it possible to select either physical release or logical release as appropriate. For example, when only a specific channel is released, selection options such as release without using relay means are expanded, User convenience is improved. When either of the two channels is released, a RESTART signal may be transmitted using the call number or channel number corresponding to the setting by the means for setting the release channel.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 shows a system configuration diagram in the present embodiment. The monitoring center 10 is connected to the forced line connection device 18 via the ISDN exchange 12. The forced line connection device 18 is connected between the ISDN switch 12 and the home DSU 14, that is, at the U point, and the emergency terminal 20 is connected to the forced line connection device 18. A home terminal 15 is connected to the home DSU 14. There can be a plurality of home terminals.
[0018]
The forced line connection device 18 includes a first communication interface (I / F) 18a, a second communication interface (I / F) 18b, a reception control unit 18c, a transmission control unit 18d, a main control unit 18e, and a terminal interface 18f. It is configured to include.
[0019]
The first communication interface 18a terminates the subscriber line to the ISDN switch 12, and when receiving from the ISDN switch 12 in the downstream direction (ISDN switch → internal terminal), the two-wire ping-pong transmission method to the four-wire transmission / reception independent transmission method. The received data is supplied to the reception control unit 18c. Also, when receiving an uplink (home terminal → ISDN exchange) from the transmission control unit 18d, the transmission is converted from the 4-wire transmission / reception independent transmission method to the 2-wire ping-pong transmission method.
[0020]
The second communication interface 18b converts the 2-wire ping-pong transmission method from the 4-wire transmission / reception independent transmission method to the transmission control unit 18d when receiving in the uplink direction from the home DSU 14. When receiving in the downlink direction from the reception control unit 18c, the 4-wire transmission / reception independent transmission method is converted to the 2-wire ping-pong transmission method. Therefore, when viewed from the home DSU 14, it is as if the forced line connection device 18 does not exist and is connected to a normal U point. The second communication interface 18b is provided with a relay for physically cutting off the connection with the home terminal.
[0021]
The reception control unit 18c extracts the D channel from the data frame at the layer 1 level when receiving a signal from the first communication interface 18a, and converts it into a frame at the layer 2 level. A layer 2 level frame generally includes a flag sequence, an address field, a control field, an information field, and a frame check sequence. In the address field, a SAPI (service access point identifier) indicating a reception point for a service provided by the layer 2 level. And a TEI (terminal termination point identifier) for identifying each terminal. In addition, there are various types of frames such as information transfer frames, monitoring frames, and unnumbered frames. The information transfer frame is used to transfer layer 3 information, and the monitoring frame can be received or confirmed for each frame. It is used for response and the like, and the unnumbered frame is used when a specific operation mode is set between the terminal and the ISDN exchange. SABME (Extended Asynchronous Balance Mode Setting) is one of the commands of this unnumbered frame, and it is possible to set the multiframe confirmation type operation mode between the terminal and the ISDN switch 12 by this.
[0022]
The transmission control unit 18d converts the data transmitted from the main control unit 18e into a layer 2 level frame, further converts it into a layer 1 level frame, and supplies the frame to the upstream direction (first communication interface 18a). In the present embodiment, a SABME signal including the TEI value supplied from the main control unit 18e is supplied to the first communication interface 18a, and a RESTART (restart) signal requesting initial setting is supplied.
[0023]
The main control unit 18e extracts the TEI value included in the downlink data received by the reception control unit 18c or the TEI value included in the uplink data received by the transmission control unit 18d, and stores and manages it in the internal memory. . Specifically, at the time of transmission, the TEI value is extracted from the CALL PROC (downlink signal) and the CONN (downlink signal) signal and stored, and at the end of the call, DISC (uplink / downlink), REL (uplink / downlink), RELCOMP The TEI value is extracted from (up / down) and erased from the memory. When an incoming call is received, a TEI value is extracted from the CALL PROC (upstream signal), ALERT (upstream signal), CONN (upstream signal), and CONNACK (downstream signal) signal and stored in the memory, and from the DISC, REL, and RELCOMP at the end of the call Extract TEI value and erase from memory. In addition to the TEI value, the main control unit 18e can also store and manage the call number and channel identifier included in the data in the memory. When the main control unit 18e receives an emergency signal from the emergency terminal 20 via the terminal interface 18f, the main control unit 18e performs call setup from the transmission control unit 18d, and when all the B channels are in communication and communication cannot be established. A SABME signal and a RESTART signal are supplied to the transmission control unit 18d by using the TEI value stored in the memory by performing processing described later. The SABME signal and the RESTART signal are transmitted to the ISDN switch 12 through the first interface 18a.
[0024]
Hereinafter, the forced line connection process will be described in more detail with reference to FIG.
[0025]
When the emergency terminal 20 detects an emergency, the forced line connection device 18 transmits a call setting to the ISDN switch 12 to notify the monitoring center 10. However, when all the B channels are in use, the release completion (reason code # 34 (no available line / channel)) is received from the ISDN switch 12, and the monitoring center 10 cannot be notified.
[0026]
Therefore, the forced line connection device 18 first instructs the second communication interface 18b to operate the relay, and physically disconnects communication between the home terminal 15 and the ISDN switch 12. Next, the SABME signal including the TEI value stored in the memory is transmitted to the ISDN switch 12, and then the RESTART signal is transmitted to the ISDN switch 12. The ISDN exchange 12 interprets that a command to be set to the multiframe confirmation type operation mode is received from the home terminal specified by the TEI value by receiving the SABME signal including the TEI value, and subsequently receives the RESTART signal. To immediately release the B channel with the in-home terminal. Since the release is based on the RESTART signal, it is released in 2 to 3 seconds, unlike the release due to time-over. After the release, the forced line connection device 18 transmits the call setting to the ISDN switch 12 again, receives the call setting reception, call and response from the ISDN switch 12, and receives information from the emergency terminal 20 to the monitoring center 10. Send. After communication with the monitoring center 10 is established, the relay of the second interface 18b is returned and physically reconnected so that communication with the home terminal is possible.
[0027]
In this way, by monitoring the TEI value during communication and transmitting the SABME signal and further the RESTART signal using this TEI value, whether the forced line connection device 18 is a home terminal specified by this TEI value. Since the command is transmitted to the ISDN switch 12 (when viewed from the ISDN switch 12, it is not possible to distinguish between the in-home terminal and the forced line connection device), it does not require complicated processing and can be simplified ( It is only necessary to monitor the TEI value), and the communication line can be quickly released to establish communication with the emergency terminal.
[0028]
In this embodiment, the SABME signal and the RESTART signal are transmitted after the relay is operated and physically disconnected. However, the relay is operated simultaneously with the disconnection by the relay or after the SABME signal and the RESTART signal are transmitted. Can also be cut.
[0029]
In this embodiment, a relay is provided in the second communication interface 18b, and this relay is operated to physically cut off the connection with the home terminal and release all the B channels. The communication interface 18b is not provided with a relay, only the frame signal of all SAPI = 0 is logically cut off (discarded) by the forced line connection device 18, and the TEI value stored in the memory of the main control unit 18e is used. The SABME signal and the RESTART signal can be transmitted to release all B channel communication while maintaining D channel communication. Further, only the frame signal of a specific SAPI = 0 is logically blocked (discarded) by referring to the data associating the stored call number information with the channel information being used, and used in the blocked frame signal. Only the 1B channel can be released by transmitting the SABME signal and the RESTART signal using the TEI value and the channel identifier. Specifically, for example, for uplink data, the transmission control unit 18d removes all SAPI = 0 or specific SAPI = 0 frames. Thereby, only the minimum necessary channel for establishing communication with the emergency terminal 20 can be released, and disconnection of D channel communication or other channels can be prevented.
[0030]
In the present embodiment, whether the relay in the second communication interface is operated to disconnect all channels and establish communication with the emergency terminal 20, or only the necessary channels are released as described above. It is also desirable to provide a switch (SW) 18g for selecting the switch 18 in the forced line connection device 18 so that the user can select which method is forcibly released and connected by operating the switch 18g.
[0031]
For example, a switch 18g capable of selecting either the A state or the B state is provided, and when the user sets the A state, the main control unit 18e sends a command to the second communication interface 18b based on this setting and relays When the user sets the switch 18g to the B state, the main control unit 18e does not operate the relay based on this setting and makes a physical connection. The frame signal of SAPI = 0 is discarded and the SABME signal or the like is transmitted. Also, when only a necessary channel is released without operating the relay, it is desirable that the switch 18g can select which of the B1 channel or the B2 channel is released. For example, a dip switch is provided as the switch 18g, a SABME including a channel number designated by the dip switch is transmitted, and only the designated channel is released.
[0032]
The embodiment of the present invention has been described above, but the present invention is similarly applied not only to a security terminal but also to a case where it is necessary to reserve a line preferentially for carrying important traffic such as a backup line. can do.
[0033]
【The invention's effect】
According to the present invention, communication between the emergency terminal and the monitoring center can be easily and quickly established even when all the channels of the ISDN line are in use.
[0034]
Also, when establishing communication with the emergency terminal, it is possible to suppress the influence on the in-home terminal during communication.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram of an embodiment.
FIG. 2 is a process explanatory diagram of the embodiment.
FIG. 3 is a configuration block diagram of a conventional apparatus.
[Explanation of symbols]
10 monitoring center, 12 ISDN exchange, 14 in-house DSU, 15 in-house terminal, 18 forced line connection device.

Claims (6)

A forced line connection device that releases communication between a home terminal connected to a home DSU and an ISDN switch and establishes communication with an emergency terminal,
Line connection means connected between the ISDN exchange and the home DSU, the line connection means,
Means for storing a TEI value in communication between the home terminal and the ISDN switch;
Means for transmitting a SABME signal and a RESTART signal to the ISDN switch using the TEI value;
A forced line connection device comprising: The apparatus of claim 1.
The means for storing stores the call number or channel identifier of the B channel used in the TEI value together with the TEI value,
The forced line connection device, wherein the transmitting means transmits the RESTART signal using the TEI value and the call number or channel identifier. The apparatus according to claim 1,
The line connection means further includes:
Relay means for physically disconnecting the connection between the home terminal and the ISDN switch;
A forced line connection device comprising: The apparatus according to claim 1,
The line connection means further includes:
Means for blocking a frame signal of SAPI = 0 transmitted and received between the in-home terminal and the ISDN switch;
A forced line connection device comprising: The apparatus according to claim 1,
The line connection means further includes:
Relay means for physically disconnecting the connection between the home terminal and the ISDN switch;
Means for blocking a frame signal of SAPI = 0 transmitted and received between the in-home terminal and the ISDN switch;
Means for selectively operating either the relay means or the means for blocking;
A forced line connection device comprising: The apparatus of claim 2.
The line connection means further includes:
Means for setting which of the two B channels to be released;
And the means for transmitting uses the call number or the channel number according to the setting in the means for setting.

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