JP7409153B2 - Gateway device, terminal management method, and program - Google Patents

Description

The present invention relates to a gateway device having a terminal management unit that communicably connects a plurality of communication lines of different protocols in accordance with a command, a terminal management method of the terminal management unit, and a computer program for the terminal management unit.

It has been confirmed that a VoIP (Voice over Internet Protocol) gateway device equipped with BRI (ISDN Basic Rate Interface) is generally connected to a BRI port via a communication line using the Q.921 protocol. Communication terminals such as digital telephones and terminal adapters are equipped with terminal management units that manage the terminals, control calls, and the like. Normally, the terminal management unit performs keep-alive for the communication terminal whose connection has been confirmed, and at this time, for example, transmits RR (Receive Ready). The terminal management unit determines that the connection with the communication terminal is valid if there is a response from the communication terminal to the keep-alive RR, and if there is no response from the communication terminal, the connection with the communication terminal is invalid. It is determined that Further, for the communication terminal determined to be invalid, a recovery operation including recovery processing such as an ID check request is performed, and an attempt is made to enable the connection with the communication terminal.

Patent Document 1 discloses an electronic exchange that recognizes and manages the number of ISDN terminals by performing keep-alive by periodically transmitting an ID check request message from an ISDN interface unit to an ISDN terminal that is a communication terminal whose connection has been confirmed. Disclosed.

Japanese Patent Application Publication No. 5-176359

However, while the recovery operation after determining that the connection is invalid in keep-alive is the recovery process predetermined by the VoIP gateway device, since various types of communication terminals can be connected to the communication line, The problem is that the recovery process is not adapted to the characteristics of each communication terminal, and as a result, the service may not be restored, or even if it is restored, the service outage period during which the connection with the communication terminal is disabled may be extended. was there.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gateway device, a terminal management method, and a program that can shorten the recovery time for a communication terminal after the connection with the communication terminal is determined to be invalid by keep-alive. It is to be.

The gateway device of the present invention is a terminal management device that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a different protocol from the first communication line in accordance with a command. a gateway device comprising: a first determining unit in which the terminal management unit determines whether a layer 1 link with the communication terminal has been established via the first communication line; a second determining means for determining whether or not reception of a layer 2 message from the communication terminal is completed after determining the establishment of the layer 1 link; and after determining completion of reception of the layer 2 message; registration requesting means for requesting registration of the communication terminal to a communication management device of the second communication line; processing means for executing keep-alive processing for the communication terminal after requesting registration of the communication terminal; a third determining means for determining whether or not there is a response from the communication terminal through the process; and at least two determining means for restoring communication with the communication terminal when there is no response from the communication terminal through the keep-alive process. a storage means storing priority data of two recovery processes; and a storage means that executes a recovery process of a first priority indicated in the priority data when there is no response from the communication terminal due to the keep-alive process; a first recovery means that determines whether or not there is a response from the communication terminal; and a first recovery means that determines whether or not there is a response from the communication terminal; a second recovery means that executes recovery processing for priorities lower than the second priority and determines whether or not there is a response from the communication terminal; and a recovery processing for priorities lower than the second priority; When there is a response from the communication terminal, the recovery process for a priority lower than the second priority becomes a new first priority recovery process instead of the first priority recovery process. The present invention is characterized in that it includes a rewriting means for rewriting the priority data in the storage means.

The terminal management method of the present invention provides a terminal that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a protocol different from that of the first communication line in accordance with a command. A terminal management method for the terminal management unit in a gateway device having a management unit, the step of determining whether a layer 1 link with the communication terminal has been established via the first communication line; After determining the layer 1 link establishment, determining whether or not the layer 2 message reception from the communication terminal is completed; and after determining the completion of the layer 2 message reception, the second step a step of requesting registration of the communication terminal to a communication management device of a communication line; a step of executing keep-alive processing for the communication terminal after the registration request of the communication terminal; a step of determining whether or not there is a response; and, if there is no response from the communication terminal due to the keep-alive processing, performing a recovery process of the first priority indicated in the priority data stored in the storage means. a step of determining whether or not there is a response from the communication terminal; and a step of determining whether or not there is a response from the communication terminal according to the first priority order recovery process; a step of determining whether or not there is a response from the communication terminal by executing a recovery process for a priority level lower than or equal to the second priority level; , the storage means is configured such that the recovery process for a priority level lower than the second priority level becomes a new recovery process for the first priority level instead of the recovery process for the first priority level. The method is characterized in that it includes the step of rewriting the priority data.

The program of the present invention includes a terminal management unit that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a protocol different from that of the first communication line in accordance with a command. A program for a method for managing the communication terminal in a gateway device having a computer, wherein a layer 1 link with the communication terminal is established in a computer of the terminal management unit via the first communication line. a step of determining whether the layer 2 message reception from the communication terminal is completed after determining the layer 1 link establishment; and a step of determining whether the layer 2 message reception from the communication terminal is completed. after determining the communication terminal, making a request to register the communication terminal to a communication management device of the second communication line; after requesting the registration of the communication terminal, executing a keep-alive process for the communication terminal; a step of determining whether or not there is a response from the communication terminal through keep-alive processing; and a step of determining whether or not there is a response from the communication terminal through keep-alive processing; executing the first priority recovery process to determine whether there is a response from the communication terminal; and if there is no response from the communication terminal due to the first priority recovery process; a step of determining whether or not there is a response from the communication terminal by executing a recovery process for the priorities below the second priority indicated in the priority data; When a response is received from the communication terminal as a result of the recovery process, the recovery process for a priority level lower than the second priority level replaces the recovery process for the first priority level and restores a new first priority level. The method is characterized in that the step of rewriting the priority order data in the storage means so that the processing is executed is performed.

According to the gateway device, terminal management method, and program of the present invention, in the recovery operation when the connection with the communication terminal is determined to be invalid in the keep-alive processing, the first recovery operation is performed when a response from the communication terminal is received. Since the priority data in the storage means is rewritten so that the priority recovery process is performed, if the connection with the communication terminal is determined to be invalid in the next keep-alive process, the subsequent recovery operation for the communication terminal will be shortened. It is possible to save time.

1 shows a communication system including a VoIP gateway device according to an embodiment of the present invention. 2 is a flowchart showing the terminal management operation of the terminal management section in the VoIP gateway device of FIG. 1. FIG. 3 is a flowchart showing a continuation of the terminal management operation shown in FIG. 2;

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a communication system including a VoIP gateway device 10 according to an embodiment of the present invention. The VoIP gateway device 10 is a device that communicably connects an IP (Internet Protocol) network and an ISDN (Integrated Services Digital Network) line, which have mutually different protocols, in response to a command such as making a call, for example.

As shown in FIG. 1, the VoIP gateway device 10 includes a BRI interface section 11, a terminal management section 12, and an IP interface section 13. A digital telephone 22 is connected to a communication port (BRI port) of the BRI interface section 11, which is a first interface section, via a communication line 21 (first communication line), which is an ISDN line. An IP network 31 (second communication line) is connected to a communication port of the IP interface unit 13, which is a second interface unit, and a SIP (Session Initiation Protocol) server 32 is connected to the IP network 31. The SIP server 32 is a server that manages and controls IP telephone services using SIP in the IP network 31.

The BRI interface unit 11 has an L2 message transmission/reception function, an L1 link status monitoring function, and an L1 link status changing function. L1 represents layer 1 and L2 represents layer 2.

The L2 message transmission/reception function is a function for transmitting and receiving layer 2 messages with a communication terminal such as the digital telephone 22 connected to the BRI interface section 11. That is, the L2 message received from the terminal management section 12 is transmitted to the communication terminal, and the L2 message received from the communication terminal is notified to the terminal management section 12. In reality, communication with the terminal management unit 12 is also performed regarding layer 1, but the details thereof will be omitted in this embodiment.

The L1 link status monitoring function is a function that monitors the layer 1 link status and notifies the terminal management unit 12 when the link status changes. The L1 link state change function is a function that changes the layer 1 link state upon receiving an L1 control request from the terminal management unit 12.

As shown in Table 1, the L1 link status is No. ACTIVATED, in which the layer 1 link of No. 1 has been established and communication at layer 2 is possible; This includes NOT ACTIVATED, which is a state in which the layer 1 link of 2 is not established and communication in layer 2 is not possible.

Further, as shown in Table 2, the contents of the layer 1 control request from the terminal management unit 12 used in the L1 link state change function include L1 link down and chip reset. L1 link down is a request to link down layer 1 and implement the layer 1 connection sequence from the beginning. The chip reset is a request to reset and initialize the devices constituting the BRI interface unit 11.

The terminal management unit 12 is composed of, for example, a microcomputer, and has an L2 message function and a terminal management function by executing a built-in software program. The L2 message function is a function for exchanging L2 messages with a communication terminal. Actual transmission and reception is performed by requesting the BRI interface unit 11 to transmit and receive L2 messages, and using the above-described L2 message transmission and reception function. The terminal management function is a function to manage the status of a communication terminal.

As shown in Table 3, the terminal status managed by the terminal management function is No. 1~No. There are four terminal states: 4. For example, the terminal status of each communication terminal is stored as data in an internal memory (not shown) of the terminal management unit 12. Internal memory corresponds to storage means. No. 1 indicates that the L1 link is not established; specifically, layer 1 indicates inactivity with NOT ACTIVATED, layer 2 indicates that TEI (Terminal Endpoint Identifier) is not assigned, and SIP indicates that the This is the state shown. No. 2 is a state in which the L1 link has been established and an ID request has not been received from the communication terminal; specifically, layer 1 indicates ACTIVATED, indicating active, layer 2 indicates TEI is not allocated, and SIP indicates deregistration. This is the state shown. No. 3 is a state in which the L1 link has been established and an ID has been assigned to the communication terminal; specifically, layer 1 is ACTIVATED indicating active, layer 2 indicates TEI has been assigned, and SIP indicates registered. state. No. 4 is a state in which the L1 link has been established, an ID has been assigned to the communication terminal, and there is no response to keepalive; specifically, layer 1 indicates active with ACTIVATED, and layer 2 indicates that the TEI has been assigned. It also indicates that the communication terminal status is being checked, and the SIP indicates deregistration. Note that TEI is an identifier that identifies a communication terminal of a communication partner, that is, an ID.

No. In the L1 link established state of No. 3, a keep-alive is performed for the communication terminal, and if there is no response to the keep-alive from the communication terminal for some reason, the L1 link is established. 4, a transition is made to the state in which the communication terminal status is being checked. No. When the status of the communication terminal is being checked in step 4, one of the plurality of recovery processes is executed in accordance with the priority order. The priority order of each restoration process is stored in the internal memory as priority order data.

As for the recovery operation, as shown in Table 4, No. 1 is restored in the initial priority order. 1~No. There are four recovery processes. Priority 1 (corresponding to the first priority) No. 1 is the transmission of an ID check request. This is a process of transmitting an ID check request to a keep-alive communication terminal. A communication terminal that receives an ID check request for an ID assigned to itself sends back an ID response in response. No. 2 in priority order (corresponding to the second priority order). 2 is the transmission of SABME (asynchronous balanced mode setting). This is a process of transmitting a SABME message to a communication terminal. Priority 3 No. 3 is L1 link down. This is a recovery process that is performed by once linking down layer 1 and establishing the layer 1 link. Priority 4 No. 4 is a BRI interface section reset. This is a recovery process that resets the devices constituting the BRI interface section 11 and starts with the initialization process.

The IP interface unit 13 has a VoIP function installed in a normal VoIP gateway, and sends and receives IP packets to and from communication partner devices including the SIP server 32 via the IP network 31. Furthermore, the IP interface section 13 analyzes the SIP message received from the SIP server 32 and notifies the terminal management section 12 of the contents of the incoming call. It also converts the notification content of the terminal management unit 12 into a SIP message and sends it to the SIP server 32. In this embodiment, only incoming messages are received from the IP network 31, and the notification contents from the terminal management unit 12 are three types: "registration request," "response (to incoming call)," and "Busy (in response to incoming call)." It is said that

In the VoIP gateway device 10 having such a configuration, when the digital telephone 22 is connected to the communication line 21 of the BRI interface unit 11, the layer 1 Exchanges will be held. This establishes a layer 1 link. When the L1 link status monitoring function described above detects the establishment of a layer 1 link, the BRI interface unit 11 notifies the terminal management unit 12 of ACTIVATED (No. 1 in Table 1) indicating the active status.

The terminal management unit 12 executes a terminal management operation when layer 1 exchange is started between the BRI interface unit 11 and the digital telephone 22 via the communication line 21.

As shown in FIGS. 2 and 3, in the terminal management operation, first, it is determined whether a layer 1 link has been established (step S10). When receiving the Layer 1 link establishment notification from the BRI interface unit 11, the terminal status of the digital telephone 22 is changed to No. 1 in Table 3. 2 (step S11). In the terminal management unit 12, the terminal status of the digital telephone 22 in the internal memory is No. 3 in Table 3 until receiving the ACTIVATE notification in step S11. 1, which is No. 1 in Table 3. It can be rewritten to the contents of 2. That is, the terminal management unit 12 manages that the layer 1 link has been established for the digital telephone 22, but that no ID request has been received from the digital telephone 22. Since the ID request has not been received, the L2 message will be awaited.

The BRI interface section 11 communicates L2 messages with the digital telephone 22 using the L2 message transmission/reception function, and upon completion of receiving the L2 message requesting ID assignment from the digital telephone 22, notifies the terminal management section 12 of this. The terminal management unit 12 determines from the notification whether or not the reception of the L2 message is completed (step S12). When the terminal management unit 12 determines that the reception of the L2 message is completed, it allocates a TEI to the digital telephone 22 (step S13). In TEI assignment, the TEI is notified to the digital telephone 22 via the BRI interface section 11. After allocating the TEI, the terminal management unit 12 sets the terminal status of the digital telephone 22 to No. 3 in Table 3. 3 (step S14). Furthermore, the terminal management unit 12 notifies the IP interface unit 13 of the registration request (step S15).

Upon receiving the registration request from the terminal management section 12, the IP interface section 13 causes the SIP server 32 to register information necessary for a telephone call, such as the address of the digital telephone 22.

In this way, the terminal status of the digital telephone 22 is No. 1 in Table 3. When the state of 3 is reached, the terminal management section 12 instructs the BRI interface section 11 to transmit an RR (Receive Ready) to the digital telephone 22 using the terminal management function described above for keep-alive (step S16). , whereby the RR is transmitted from the BRI interface section 11 to the digital telephone 22. The RR is transmitted as a transmission signal to the digital telephone 22 via the communication line 21. The terminal management unit 12 determines whether a response signal to the RR is received each time the RR is transmitted (step S17). If the digital telephone 22 continues to be connected to the communication line 21, upon receiving the RR, the digital telephone 22 transmits a response signal to the VoIP gateway device 10 in response to the RR. Upon receiving the response signal, the BRI interface section 11 notifies the terminal management section 12 of the reception of the response signal.

In step S17, when the terminal management unit 12 receives a notification of receipt of a response signal within a predetermined period from the RR transmission command, the terminal management unit 12 receives a response signal from the RR transmission command. 3 is maintained (step S18). If the reception notification of the response signal is not received within the predetermined period, it is determined whether the RR has been transmitted four times (step S19). The predetermined period is, for example, the time it takes from transmitting the RR to receiving the response signal, or the time taking into account a slight delay. If the number of RR transmissions has not reached four, the BRI interface unit 11 is instructed to retransmit the RR to the digital telephone 22 (step S20). After transmitting the RR, if no response signal is received within a predetermined period, the RR is retransmitted. If a response signal to the RR is not received even though the RR has been retransmitted three times (a total of four RR transmissions), the terminal management unit 12 determines the terminal status of the digital telephone 22. is No. in Table 3. 4 (step S21).

After executing step S21, the terminal management unit 12 reads the priority data from the internal memory and instructs the BRI interface unit 11 to perform recovery processing for priority 1 (step S22). The initial priority level 1 recovery process is an ID check request, and in this case, the BRI interface section 11 is instructed to send the ID check request to the digital telephone 22. An ID check request is transmitted from the BRI interface section 11 to the digital telephone 22. After instructing the restoration process of priority 1, the terminal management unit 12 determines whether there is a response from the digital telephone 22 (step S23). For example, if there is an ID response from the digital telephone 22 in response to an ID check request, the terminal management unit 12 will check the terminal status of the digital telephone 22 according to No. 3 in Table 3. The state is returned to No. 3 (step S24). After executing step S24, the terminal management unit 12 returns to step S16 and instructs the BRI interface unit 11 to transmit an RR for keep-alive.

If there is no response in step S23, the terminal management unit 12 instructs the BRI interface unit 11 to perform recovery processing for priority 2 indicated in the priority data (step S25). The initial priority level 2 recovery process is the transmission of SABME, and in this case, the BRI interface unit 11 is instructed to transmit SABME to the digital telephone 22 . In response to the SABME transmission command, the BRI interface section 11 transmits an SABME message to the digital telephone 22. After instructing the recovery process of priority 2, the terminal management unit 12 determines whether there is a response from the digital telephone 22 (step S26). For example, in the case of SABME message transmission, the terminal management unit 12 determines whether there is a response from the digital telephone 22 in the asynchronous balanced mode. If it is determined in step S26 that the BRI interface section 11 has received a response from the digital telephone 22, the terminal management section 12 records the terminal status of the digital telephone 22 as No. 3 in Table 3. 3 (step S27). Furthermore, the terminal management unit 12 rewrites the priority data in the internal memory in order to change the priority of the recovery process (step S28). In other words, as shown in Table 5, the recovery process with priority 2 of the priority data (sending SABME in the initial priority) is set as the new priority 1, and the recovery process with priority 1 (initial priority) is set as the new priority 1. In this case, transmission of ID check request) is given priority 2.

After executing step S28, the terminal management unit 12 returns to step S16 and instructs the BRI interface unit 11 to transmit an RR for keep-alive.

If there is no response from the digital telephone 22 in step S26, the terminal management unit 12 instructs the BRI interface unit 11 to perform recovery processing of priority 3 indicated in the priority data (step S29). The initial priority 3 recovery process is L1 link down, and in this case, the terminal management unit 12 instructs the BRI interface unit 11 to bring down the L1 link, so the BRI interface unit 11 brings down the layer 1 link once. , starting from layer 1 link establishment. After instructing the restoration process of priority 3, the terminal management unit 12 determines whether there is a response from the digital telephone 22 (step S30). If it is determined in step S30 that the response from the digital telephone 22 has been received by the BRI interface section 11, the terminal management section 12 records the terminal status of the digital telephone 22 as No. 3 in Table 3. 3 (step S31). Furthermore, the terminal management unit 12 rewrites the priority data in the internal memory in order to change the priority of recovery processing (step S32). That is, the restoration process of priority 3 of the priority data is set as priority 1, and the restoration processes of priority 1 and 2 are set as priorities 2 and 3, respectively. After executing step S32, the terminal management unit 12 returns to step S16 and instructs the BRI interface unit 11 to transmit an RR for keep-alive.

If there is no response from the digital telephone 22 in step S30, the terminal management unit 12 instructs the BRI interface unit 11 to perform recovery processing of priority 4 indicated in the priority data (step S33). The initial priority level 4 recovery process is to reset the BRI interface unit, and in this case, the terminal management unit 12 instructs the BRI interface unit 11 to reset, so the BRI interface unit 11 resets the devices that constitute itself. Then, initialization processing is performed, and the above-mentioned layer 1 link establishment is performed. After instructing the recovery process with priority level 4, the terminal management unit 12 determines whether there is a response from the digital telephone 22 (step S34). If it is determined in step S34 that the BRI interface section 11 has received a response from the digital telephone 22, the terminal management section 12 records the terminal status of the digital telephone 22 as No. 3 in Table 3. The state is returned to No. 3 (step S35). Furthermore, the terminal management unit 12 rewrites the priority data in the internal memory in order to change the priority of recovery processing (step S36). That is, the recovery process of priority level 4 of the priority data is set to priority level 1, and the recovery processes of priority level 1, 2, and 3 are set to priority levels 2, 3, and 4, respectively.

If there is no response from the digital telephone 22 in step S34, it means that keep-alive with the digital telephone 22 could not be restored even after all the recovery processes were tried, and in that case, the terminal management unit 12 The terminal status is shown in Table 3. The terminal management is changed to state 2 (step S37). After executing step S37, the terminal management unit 12 returns to step S12 and determines whether an L2 message requesting ID assignment has been received from the digital telephone 22.

In the embodiment described above, the execution of step S10 by the terminal management unit 12 corresponds to the first determination means, and the execution of step S12 corresponds to the second determination means. Further, the execution of step S13 of the terminal management unit 12 corresponds to an allocation means, the execution of step S15 corresponds to a registration request means, the execution of step S16 corresponds to a processing means, and the execution of step S17 corresponds to a third determination means. It corresponds to the means. Further, execution of steps S22 and S23 by the terminal management unit 12 corresponds to a first recovery means, execution of steps S25 and S26 corresponds to a second recovery means, and execution of step S28 corresponds to a rewriting means.

In this way, the terminal management unit 12 instructs the recovery process according to the priority order. For example, when a command is issued to transmit a SABME with priority 2 and a response is received from the digital telephone 22, the terminal status of the digital telephone 22 is changed to No. 2 in Table 3. After returning to state 3, SABME transmission becomes priority 1. Therefore, that No. After returning to state 3, if there is no response to keepalive by sending RR again three times, according to the priority of recovery operation at that time, instead of recovery processing by initial ID check request, recovery performance is Therefore, SABME transmission with priority 1 is performed first, and an attempt is made to restore keep-alive with the digital telephone 22. This is because there is a history of recovery in SABME transmission, so there is a high possibility of recovery.

Note that the recovery operation priority can be initialized and reset to the initial priority by performing a physical L1 link down operation (not an L1 link down due to a recovery operation).

Therefore, in the embodiment described above, the plurality of recovery processes in the recovery operation in a state where the digital telephone 22 has not responded to the RR transmission in the keep-alive four times in a row are executed in accordance with the priority order. In the initial priority recovery operation, if there is no response from the digital telephone 22 after sending an ID check request, which is a recovery process with priority 1, the SABME is sent as a recovery process with priority 2, and that SABME is sent. If there is a response from the digital telephone 22 to the transmission, SABME transmission becomes the priority 1 recovery process. After that, when the digital telephone 22 does not respond to the RR transmission in keep-alive four times in a row again, in the recovery operation, SABME transmission, which has newly been given priority 1, is performed first. Therefore, if there is no response from the digital telephone 22 in the second keep-alive, the connection with the digital telephone 22 can be restored in a short time, and the service suspension period can be shortened. Note that the number of times the RR is transmitted again when there is no response from the digital telephone 22 to the RR transmission in keep-alive is not limited to three times. For example, RR transmission may be repeated four or more times.

Furthermore, since the operation automatically prioritizes and executes recovery processing that has a proven track record, operations by maintenance personnel and setting changes for each communication terminal can be eliminated.

Furthermore, physical L1 link down operation resets the priority of recovery processing in the recovery operation, so when changing the communication terminal to another terminal, the priority will return to the initial The assigned priority order will not be affected every time the terminal is changed.

In the above-described embodiment, an example is described in which recovery is performed using the recovery processing shown in Table 4, but the recovery processing can also be modified in accordance with the characteristics of the VoIP gateway device or communication terminal.

Further, in the embodiment described above, an example was described in which the recovery operation is performed according to the priority order of recovery processing shown in Table 4, but even if the priority order is changed, No. After executing the recovery process No. 1 without fail, the recovery process may be executed according to the changed priority order.

Furthermore, in the embodiment described above, only the digital telephone 22 is connected as a communication terminal to the communication port of the BRI interface unit 11 via the communication line 21, but other communication terminals are connected to the communication port via the communication line 21. A plurality of communication terminals such as digital telephones and terminal adapters may be connected.

10 VoIP gateway device 11 BRI interface section 12 terminal management section 13 IP interface section 21 communication line 22 digital telephone 31 IP network 32 SIP server

Claims (13)

The gateway device includes a terminal management unit that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a protocol different from that of the first communication line in accordance with a command. hand,
The terminal management department
a first determining means for determining whether a layer 1 link with the communication terminal has been established via the first communication line;
a second determining means for determining whether or not reception of a layer 2 message from the communication terminal is completed after determining the establishment of the layer 1 link;
registration requesting means for requesting registration of the communication terminal to a communication management device of the second communication line after determining completion of receiving the layer 2 message;
processing means for executing a keep-alive process for the communication terminal after a registration request for the communication terminal;
third determining means for determining whether or not there is a response from the communication terminal through the keep-alive processing;
Storage means storing priority data of at least two recovery processes for restoring communication with the communication terminal when there is no response from the communication terminal due to the keep-alive process;
If there is no response from the communication terminal due to the keep-alive process, a first priority recovery process indicated in the priority data is executed to determine whether or not there is a response from the communication terminal. 1 recovery means,
If there is no response from the communication terminal due to the recovery process for the first priority, the recovery process for a priority lower than or equal to the second priority indicated in the priority data is executed to recover the response from the communication terminal. a second recovery means for determining whether there is a response;
If there is a response from the communication terminal due to the recovery process for the priority level below the second priority level, the recovery process for the priority level below the second priority level becomes the recovery process for the first priority level. A gateway device comprising: rewriting means for rewriting the priority order data in the storage means so that a new first priority order restoration process is performed instead. 2. The gateway device according to claim 1, wherein the terminal management unit further includes an assignment unit that assigns an ID to the communication terminal after determining completion of reception of the layer 2 message. The processing means performs RR transmission to the first communication line toward the communication terminal in the keep -alive processing,
2. The gateway device according to claim 1, wherein the third determining means determines whether there is a response from the communication terminal to the RR transmission. When the third determining means determines that there is no response from the communication terminal to the RR transmission, the processing means retransmits the RR to the first communication line toward the communication terminal. The gateway device according to claim 3, characterized in that: If the third determining means determines that there is no response from the communication terminal to the retransmission of the RR, the processing means transmits the RR transmission to the first communication line toward the communication terminal. 5. The gateway device according to claim 4, wherein the processing is performed again. After the processing means transmits the RR for the third time, if the third determination means determines that there is no response from the communication terminal to the retransmission of the RR, the first recovery 6. The gateway device according to claim 5, wherein the means starts execution of the first priority restoration process. The initial recovery process for the first priority level stored as the priority level data in the storage means is ID check request transmission, and the initial recovery process for the second priority level is SABME transmission. The gateway device according to claim 1. a first interface unit to which the first communication line is connected and communicates with the communication terminal; a second interface unit to which the second communication line is connected and communicates with the communication management device;
The gateway device according to claim 1, wherein the terminal management section is connected to the first interface section and the second interface section. 2. The gateway device according to claim 1, wherein the first communication line is an ISDN line, and the second communication line is an IP network. 10. The gateway device according to claim 9 , wherein the communication terminal is a digital telephone, and the communication management device is a SIP server connected to the IP network. 2. The gateway device according to claim 1, wherein the priorities indicated in the priority data are initialized by a physical link down operation of the layer 1. In the gateway device, the gateway device includes a terminal management unit that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a protocol different from that of the first communication line in accordance with a command. A terminal management method by a terminal management department,
determining whether a layer 1 link with the communication terminal has been established via the first communication line;
After determining the layer 1 link establishment, determining whether or not the layer 2 message reception from the communication terminal is completed;
After determining that the layer 2 message reception is completed, requesting the communication terminal to be registered in the communication management device of the second communication line;
After requesting the registration of the communication terminal, executing a keep-alive process for the communication terminal;
determining whether or not there is a response from the communication terminal through the keep-alive processing;
If there is no response from the communication terminal due to the keep-alive process, whether there is a response from the communication terminal by executing a recovery process of the first priority indicated in the priority data stored in the storage means. a step of determining whether
If there is no response from the communication terminal due to the recovery process for the first priority, the recovery process for a priority lower than or equal to the second priority indicated in the priority data is executed and from the communication terminal. a step of determining whether there is a response;
If there is a response from the communication terminal due to the recovery process for the priority level below the second priority level, the recovery process for the priority level below the second priority level becomes the recovery process for the first priority level. A terminal management method comprising the step of rewriting the priority order data in the storage means so that a new first priority order restoration process is performed instead. In the gateway device, the gateway device includes a terminal management unit that communicably connects a first communication line to which a communication terminal is connected and a second communication line having a protocol different from that of the first communication line in accordance with a command. A program for a method of managing communication terminals,
On the computer of the terminal management department,
determining whether a layer 1 link with the communication terminal has been established via the first communication line;
After determining the layer 1 link establishment, determining whether or not the layer 2 message reception from the communication terminal is completed;
After determining that the layer 2 message reception is completed, requesting the communication terminal to be registered in the communication management device of the second communication line;
After requesting the registration of the communication terminal, executing a keep-alive process for the communication terminal;
determining whether or not there is a response from the communication terminal through the keep-alive processing;
If there is no response from the communication terminal due to the keep-alive process, whether there is a response from the communication terminal by executing a recovery process of the first priority indicated in the priority data stored in the storage means. a step of determining whether
If there is no response from the communication terminal due to the recovery process for the first priority, the recovery process for a priority lower than or equal to the second priority indicated in the priority data is executed and from the communication terminal. a step of determining whether there is a response;
If there is a response from the communication terminal due to the recovery process for the priority level below the second priority level, the recovery process for the priority level below the second priority level becomes the recovery process for the first priority level. A program characterized in that the program causes the program to execute the step of rewriting the priority data in the storage means so that a new first priority restoration process is performed instead.

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