JP5681137B2 - Telephone system and operation method thereof - Google Patents

Description

The present invention relates to telephone systems and operation methods.

  As a conventional additional service of the telephone connection service, there is a busy transfer service for switching a connection to a transfer destination registered in advance when the terminal is busy. In this service, since it is transferred after confirming that the terminal is busy, the specification is such that the call is not transferred unless the busy state can be determined due to a network failure or the like.

SIP: Session Initiation Protocol, [online], [Search February 23, 2012], Internet <URL: http://www.potaroo.net/ietf/rfc/PDF/rfc3261.pdf>

  FIG. 9 is a sequence diagram showing a conventional busy transfer sequence.

  The calling terminal A transmits a call establishment request (Invite) to the called SIP server D (S201). The call processing control unit 12A of the called-side SIP server D acquires the subscriber information from the subscriber information database 11A (S203), the called-side terminal B is busy (S205), and the talk in the subscriber information If the busy transfer flag is on, that is, if busy transfer is set in the called terminal B (S207), the transmission destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information (S209). Thereby, the call processing control unit 12A does not transmit the call establishment request to the called terminal B, but transmits it to the transfer destination terminal C which is the rewritten transmission destination (S211). The transfer destination terminal C transmits a provisional response (18x) to the called-side SIP server D (S213), and the called-side SIP server D transmits a provisional response to the calling-side terminal A (215).

  FIG. 10 is a sequence diagram showing a sequence in the case where the called terminal B to which busy transfer is set is affected.

  If the communication path to the callee terminal B is interrupted due to the damage of the callee terminal B (S221), the callee SIP server D cannot communicate with the callee terminal B and therefore cannot determine whether the call is busy. (S205). That is, since the call establishment request cannot be transferred to the transfer destination terminal C as in step S211 of FIG. 9, the call processing control unit 12A of the callee SIP server D calls the caller terminal A after a predetermined time. Establishment request O. (Timeout) is transmitted (S223).

  FIG. 11 is a sequence diagram showing a sequence when the called-side SIP server D is affected.

  When the destination SIP server D is damaged (S231), the communication path from the relay server E to the destination SIP server D is interrupted (S233).

  Even in such a situation, the calling terminal A transmits a call establishment request (Invite) to the calling SIP server F (S241).

  The call processing control unit 12A of the originating SIP server F acquires the subscriber information from the subscriber information database 11A (S243), and the transmission destination of the call establishment request does not match the subscriber telephone number in the subscriber information (S244), a call establishment request is transmitted to the relay server E (S245).

  Since the relay server E cannot connect to the destination SIP server D (S246), it transmits a call establishment request NG to the originating SIP server F (S247). The calling-side SIP server F transmits a call establishment request NG to the calling-side terminal A (S249).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a SIP server capable of transferring a call even when a terminal for which busy transfer is set is affected and an operating method thereof. Is to provide.

  Another object of the present invention is to provide a telephone system that can transfer a call even when a SIP server that accommodates a terminal for which busy transfer is set is damaged, and an operating method thereof. is there.

The first aspect of the present invention is a telephone system comprising a plurality of SIP servers, an external database device, and a relay server, wherein each SIP server has a subscriber telephone number that is a subscriber's telephone number for each subscriber, The external database comprising a subscriber information database storing subscriber information including a busy transfer flag indicating necessity of busy transfer, a victim flag indicating presence / absence of a disaster, and transfer destination information indicating a transfer destination. If the apparatus cannot communicate with a mirror database that is a duplicate of each of the subscriber information databases, and any of the SIP servers, all the damages of the mirror database generated from the subscriber information database of the SIP server A mirror database management unit for turning on the operator flag, and the relay server, when a call establishment request arrives, If communication with the SIP server corresponding to the destination of the establishment request is attempted and communication is not possible, the call establishment request is connected from the mirror database generated from the subscriber information database of the SIP server and connected to the external database device. The subscriber information including the subscriber telephone number that matches the destination telephone number is searched, and it is determined whether or not both the victim flag and the busy transfer flag in the subscriber information are on. If both of the medium transfer flags are on, the transmission destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information.

The second aspect of the present invention is a telephone system comprising a plurality of SIP servers and an external database device, wherein each SIP server has, for each subscriber, a subscriber telephone number which is a subscriber's telephone number, busy transfer A subscriber information database storing subscriber information including a busy transfer flag indicating whether or not a victim is involved, a victim flag indicating the presence or absence of a disaster, and transfer destination information indicating a transfer destination, and the external database device includes: If the mirror database, which is a copy of each subscriber information database, cannot communicate with any of the SIP servers, all the victim flags of the mirror database generated from the subscriber information database of the SIP server are displayed. A mirror database management unit to be turned on, the call processing control unit of each SIP server, if a call establishment request has arrived, If the subscriber information is obtained from the subscriber information database and the transmission destination of the call establishment request does not match the subscriber telephone number in the subscriber information, the connection is made to the external database device, and the call establishment request From the mirror database generated from the subscriber information database of the SIP server corresponding to the transmission destination, the subscriber information including the subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request is retrieved, and the subscriber information It is determined whether or not both the affected person flag and the busy transfer flag are on, and if both the affected person flag and the busy transfer flag are on, the transmission destination information in the subscriber information is determined as the transmission destination of the call establishment request. It is characterized by rewriting based on

A third aspect of the present invention is a method of operating a telephone system comprising a plurality of SIP servers, an external database device, and a relay server, wherein the SIP server is a subscriber telephone that is a subscriber telephone number for each subscriber. A subscriber information database in which subscriber information including a number, a busy transfer flag indicating whether or not busy transfer is required, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination is stored; The external database device includes a mirror database that is a copy of each subscriber information database, and the operation method is such that the mirror database management unit of the external database device cannot communicate with any of the SIP servers. In addition, it is necessary to turn on all the victim flags in the mirror database generated from the subscriber information database of the SIP server. If the relay server receives a call establishment request, the relay server attempts to communicate with the SIP server corresponding to the transmission destination of the call establishment request, and the relay server cannot communicate with the SIP server. The step of connecting to the external database device, and the relay server includes a subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request from the mirror database generated from the subscriber information database of the SIP server Searching the subscriber information; the relay server determining whether both the victim flag and the busy transfer flag in the subscriber information are on; and the relay server determining the victim flag and the talk. Rewriting the transmission destination of the call establishment request based on the transfer destination information in the subscriber information if both of the medium transfer flags are on. And butterflies.

A fourth aspect of the present invention is a method of operating a telephone system comprising a plurality of SIP servers and an external database device, wherein each SIP server has a subscriber telephone number, which is a subscriber's telephone number, for each subscriber, The external database comprising a subscriber information database storing subscriber information including a busy transfer flag indicating necessity of busy transfer, a victim flag indicating presence / absence of a disaster, and transfer destination information indicating a transfer destination. The apparatus includes a mirror database that is a copy of each subscriber information database, and the operation method is such that the mirror database management unit of the external database apparatus cannot communicate with any of the SIP servers. Turning on all victim flags in the mirror database generated from the subscriber information database of the SIP server; If the call processing control unit of the SIP server receives a call establishment request, the call processing control unit obtains the subscriber information from the subscriber information database, and the call processing control unit If it does not match the subscriber telephone number in the subscriber information, the step of connecting to the external database device, and the call processing control unit is a subscriber information database of the SIP server corresponding to the transmission destination of the call establishment request A process of retrieving subscriber information including a subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request from the mirror database generated from the call database, and the call processing control unit includes a victim in the subscriber information. Determining whether both the flag and the busy transfer flag are on, and if the call processing control unit determines that both the victim flag and the busy transfer flag are on, the call establishment request is transmitted. Above and characterized in that it comprises a step of rewriting based on the destination information in the subscriber information.

According to the first , second , third , and fourth aspects of the present invention, a call can be transferred even when a SIP server that accommodates a terminal for which busy transfer is set is affected.

It is a lineblock diagram of the telephone system concerning a 1st embodiment. 2 is a block diagram showing a schematic configuration of each SIP server 1. FIG. It is a figure which shows an example of a structure and content of the subscriber information database. It is a sequence diagram which shows a sequence when the terminal to which busy transmission is set in the first embodiment is affected. It is a block diagram of the telephone system which concerns on 2nd Embodiment. 2 is a block diagram showing a schematic configuration of an external database device 20. FIG. It is a sequence diagram which shows a sequence in case the SIP server 1 which accommodates the terminal to which busy transmission was set in 2nd Embodiment suffered. It is a sequence diagram which shows a sequence when the SIP server 1 which accommodates the terminal to which busy transfer is set in the third embodiment is affected. It is a sequence diagram which shows the sequence of the conventional busy transmission. It is a sequence diagram which shows a sequence when the called terminal B to which busy transfer is set is affected. It is a sequence diagram which shows a sequence when the callee side SIP server D suffers from a disaster.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a configuration diagram of a telephone system according to the first embodiment.

  The telephone system includes a plurality of SIP servers 1 and a network composed of one or more relay servers 2. Each SIP server 1 is connected to this network via a communication path. In addition, one or more terminals 3 are connected (accommodated) to each SIP server 1 via a communication path. FIG. 2 is a block diagram showing a schematic configuration of each SIP server 1.

  The SIP server 1 includes a subscriber information database 11 in which subscriber information including information on the connected terminal 3 and a flag set by a subscriber using the terminal 3 is stored, and a call that has arrived at the SIP server 1. And a call processing control unit 12 that performs processing and control.

  FIG. 3 is a diagram showing an example of the configuration and contents of the subscriber information database 11.

  The subscriber information database 11 includes subscriber information for each subscriber. The subscriber information includes a subscriber telephone number that is the telephone number of the terminal 3 used by the subscriber, and a talk indicating whether or not busy transfer is necessary. A middle transfer flag, a victim flag indicating the presence or absence of a disaster, and transfer destination information indicating a transfer destination are included. The subscriber information also includes a subscriber ID, a no-response transfer flag, a no-response transfer response waiting time, and the like.

  The busy transfer flag is set to ON if the subscriber desires busy transfer.

  On the other hand, the victim flag is, for example, when the DHCP lease timer expires or when the SIP Register timer expires, or when Megaco is disconnected between the SIP server 1 and the router, or between the terminal and the server. It is automatically set to ON when any abnormality is detected in the communication and the device related to the communication. Alternatively, the victim flag is manually turned on, for example, at the discretion of the maintenance person. Alternatively, the victim flag is set to ON by an application from a subscriber, for example.

  FIG. 4 is a sequence diagram illustrating a sequence in a case where a terminal for which busy forwarding is set in the first embodiment is affected.

  In FIG. 4, the calling terminal A is a terminal 3 that is a starting point for transmitting a call establishment request (Invite). The called terminal B is the terminal 3 that is the initial transmission destination of the call establishment request. The transfer destination terminal C is the terminal 3 that is the transfer destination of the call establishment request. The called-side SIP server D is a SIP server 1 that accommodates the called-side terminal B.

  First, when the communication path to the called terminal B is disconnected (S1), the corresponding victim flag in the subscriber information database 11 is turned on by the method described above (S3).

  For example, the calling terminal A transmits a call establishment request (Invite) with the called terminal B as an initial transmission destination, and the call establishment request is received by the called SIP server D (S11).

  When the call processing control unit 12 of the called-side SIP server D receives the call establishment request in this way, the subscriber telephone number that matches the telephone number of the transmission destination set in the call establishment request is obtained from the subscriber information database 11. The subscriber information including is searched (S13).

  Next, the call processing control unit 12 determines whether or not both the affected person flag and the busy transfer flag in the subscriber information are on (S14, S15).

  If both the victim flag and the busy transfer flag in the subscriber information are on, the call processing control unit 12 rewrites the transmission destination of the call establishment request based on the transfer destination information in the subscriber information (S17).

  Thereby, the call establishment request is not transmitted to the destination terminal B, but is transmitted to the transfer destination terminal C based on the rewritten transmission destination (S19).

  The transfer destination terminal C transmits a provisional response (18x) to the called side SIP server D (S21), and the called side SIP server D transmits a provisional response to the calling side terminal A (S23).

  Therefore, according to the first embodiment, the SIP server 1 determines, for each subscriber, the subscriber telephone number that is the subscriber's telephone number, the busy transfer flag that indicates whether or not busy transfer is necessary, and whether or not there is a disaster. If a call establishment request arrives, the subscriber information database 11 stores the subscriber information database 11 in which the subscriber information including the disaster victim flag indicating the transfer destination and the transfer destination information indicating the transfer destination is stored. The subscriber information including the subscriber telephone number that matches the destination telephone number is retrieved (S13), and it is determined whether or not both the affected person flag and the busy transfer flag in the subscriber information are on (S14). S15), if both the victim flag and the busy transfer flag are on, the transmission destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information (S17). In, it is possible even if a terminal busy transfer is set has afflicted performs call forwarding.

  In the first embodiment, the specific terminal 3 is the calling terminal A, the callee terminal B, and the transfer destination terminal C, and the specific SIP server 1 is the callee SIP server D. The destination terminal B, the transfer destination terminal C, and the destination SIP server D may be any terminal 3 or SIP server 1, and the same processing is performed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the second embodiment, the same or similar apparatus and apparatus configuration as those in the first embodiment are used, and the same or similar elements are redundantly described by using the reference numerals used in the first embodiment. For brevity, the description will focus on matters different from the first embodiment.

  FIG. 5 is a configuration diagram of a telephone system according to the second embodiment.

  The difference from FIG. 1 is that an external database device 20 is provided in a network including the relay server 2 and can communicate with each relay server 2.

  FIG. 6 is a block diagram showing a schematic configuration of the external database device 20.

  The external database device 20 is a copy of the subscriber information database 11 of the SIP server 1 when the mirror database 201 which is a copy of each subscriber information database 11 and the SIP server 1 cannot communicate. A mirror database management unit 202 that turns on all the victim flags of the mirror database 201.

  FIG. 7 is a sequence diagram showing a sequence in the case where the SIP server 1 that accommodates a terminal for which busy forwarding is set in the second embodiment is affected.

  In FIG. 7, a calling terminal A is a terminal 3 that is a starting point for transmitting a call establishment request (Invite). The transfer destination terminal C is the terminal 3 that is the transfer destination of the call establishment request. The called-side SIP server D is a SIP server 1 that accommodates the called-side terminal B. The relay server E is one of the relay servers 2. The originating side SIP server F is the SIP server 1 that accommodates the originating side terminal A. The transfer destination SIP server G is the SIP server 1 that accommodates the transfer destination terminal C.

  The external database device 20 acquires the data in the subscriber information database 11 from each SIP server 1 including the destination SIP server D (S30), and generates a mirror database 201 that is a copy of the subscriber information database 11. (S31).

  For example, the called-side SIP server D is affected (S40), and the communication path between the relay server E and the called-side SIP server D is disconnected (S41). Similarly, the communication path between the external database device 20 and the destination SIP server D is disconnected.

  The mirror database management unit 202 of the external database device 20 determines that the destination SIP server D does not communicate with the destination SIP server D because the communication path between the destination SIP servers D is disconnected. All the victim flags of the mirror database 201 generated by copying the subscriber information database 11 are turned on (S33). Alternatively, all the victim flags of the mirror database 201 may be turned on by judgment of the maintenance person.

  Even in such a case, the calling terminal A transmits a call establishment request (Invite) to the calling SIP server F (S51).

  The call processing control unit 12 of the originating SIP server F acquires subscriber information from the subscriber information database 11 (S53), and the transmission destination of the call establishment request does not match the subscriber telephone number in the subscriber information (S54), a call establishment request is transmitted to the relay server E (S55).

  If the call establishment request arrives and the destination SIP server D accommodates the destination terminal of the call establishment request, the relay server E tries to communicate with the destination SIP server D (S57).

  The relay server E is connected to the external database device 20 because the communication path with the destination SIP server D is not available and communication is not possible (S59).

  Next, the relay server E searches the mirror database 201 generated from the subscriber information database 11 of the destination SIP server D for subscriber information including a subscriber telephone number that matches the destination telephone number of the call establishment request. (S61).

  Next, the relay server E determines whether or not both the affected person flag and the busy transfer flag in the subscriber information are on (S63, S65).

  If both the victim flag and the busy transfer flag in the subscriber information are on, the relay server E rewrites the transmission destination of the call establishment request based on the transfer destination information in the subscriber information (S67).

  The relay server E transmits a call establishment request to the transfer destination SIP server G based on the rewritten transmission destination (S69).

  The call processing control unit 12 of the transfer destination SIP server G transmits a call establishment request to the transfer destination terminal C based on the transmission destination (S71).

  The transfer destination terminal C transmits a provisional response (18x) to the transfer destination SIP server G (S73), and the transfer destination SIP server G transmits a provisional response to the relay server E (S75). The relay server E transmits a provisional response to the originating SIP server F (S77), and the originating SIP server F transmits a provisional response to the originating terminal A (S79).

  Therefore, the telephone system according to the second embodiment includes a plurality of SIP servers 1, an external database device 20, and a relay server 2. Each SIP server 1 has a subscriber telephone number for each subscriber. Subscriber information in which subscriber information including a subscriber telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination is stored. When the external database device 20 includes the database 11 and the mirror database 201, which is a copy of each subscriber information database, cannot communicate with any of the SIP servers 1, the subscriber information database of the SIP server 1 11 to turn on all the victim flags of the mirror database 201 generated from the mirror database 201 (S33). When the call establishment request arrives, the relay server 2 (E) tries to communicate with the SIP server 1 corresponding to the transmission destination of the call establishment request (S57). (S59), subscriber information including a subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request from the mirror database 201 generated from the subscriber information database 11 of the SIP server 1 (D). (S61), it is determined whether both the victim flag and the busy transfer flag in the subscriber information are on (S63, S65). If both the victim flag and the busy transfer flag are on, Since the destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information (S67), the SIP server that accommodates the terminal set to busy transfer has been damaged. Even if it is possible to perform the call forwarding.

  In the second embodiment, the specific terminal 3 is the calling terminal A, the called terminal B, and the transfer destination terminal C, and the specific SIP server 1 is the calling SIP server F and the transfer destination SIP server G. However, the originating terminal A, the terminating terminal B, the transfer destination terminal C, the originating side SIP server F, and the transfer destination SIP server G may be any terminal 3 or SIP server 1, and the same processing is performed. .

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the third embodiment, the same or similar apparatus and apparatus configuration as those in the second embodiment are used, and the same or similar elements are redundantly described by using the reference numerals used in the first embodiment. For the sake of brevity, the description will focus on matters different from those of the second embodiment.

  FIG. 8 is a sequence diagram showing a sequence in the case where the SIP server 1 that accommodates a terminal for which busy forwarding is set in the third embodiment is affected.

  Since steps S30 to S51 are the same as those in FIG. 7 (second embodiment), the description thereof is omitted.

  The call processing control unit 12 of the originating SIP server F acquires subscriber information from the subscriber information database 11 (S53), and the transmission destination of the call establishment request does not match the subscriber telephone number in the subscriber information (S54), the external database device 20 is connected (S81).

  Next, the call processing control unit 12 obtains subscriber information including a subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request from the mirror database 201 generated from the subscriber information database 11 of the destination SIP server D. Is searched (S83).

  Next, the call processing control unit 12 determines whether or not both the affected person flag and the busy transfer flag in the subscriber information are on (S85, S87).

  If both the victim flag and the busy transfer flag in the subscriber information are on, the call processing control unit 12 rewrites the transmission destination of the call establishment request based on the transfer destination information in the subscriber information (S89).

  The call processing control unit 12 transmits a call establishment request to the relay server E based on the rewritten transmission destination (S91).

  The relay server E transmits a call establishment request (Invite) to the transfer destination SIP server G based on the transmission destination (S93).

  The call processing control unit 12 of the transfer destination SIP server G transmits a call establishment request (Invite) to the transfer destination terminal C based on the transmission destination (S95).

  The transfer destination terminal C transmits a provisional response (18x) to the transfer destination SIP server G (S97), and the transfer destination SIP server G transmits a provisional response to the relay server E (S99). The relay server E transmits a provisional response to the originating SIP server F (S101), and the originating SIP server F transmits a provisional response to the originating terminal A (S103).

  Therefore, the telephone system according to the third embodiment includes a plurality of SIP servers 1 and the external database device 20, and each SIP server 1 is a subscriber whose subscriber telephone number is for each subscriber. A subscriber information database 11 is stored in which subscriber information including a telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not a disaster has occurred, and transfer destination information indicating a transfer destination is stored. The external database device 20 is generated from the subscriber information database 11 of the SIP server 1 when the mirror database 201, which is a duplicate of each subscriber information database, cannot communicate with any of the SIP servers 1. A mirror database management unit 202 for turning on all victim flags in the mirror database 201 (S33), and a SIP server When a call establishment request arrives, the call processing control unit 12 of the server 1 (F) acquires subscriber information from the subscriber information database 11 (S53), and the transmission destination of the call establishment request is within the subscriber information. If it does not match the subscriber telephone number (S54), it connects to the external database device 20 (S81), and from the mirror database generated from the subscriber information database of the SIP server corresponding to the transmission destination of the call establishment request, The subscriber information including the subscriber telephone number that matches the destination telephone number of the call establishment request is searched (S83), and it is determined whether or not both the affected person flag and the busy transfer flag in the subscriber information are on. If both the victim flag and the busy transfer flag are on (S85, S87), the transmission destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information (S89). Because, it can even when the SIP server 1 that accommodates a terminal busy transfer is set to (D) was afflicted performs call forwarding.

  In the third embodiment, the specific terminal 3 is the calling terminal A, the called terminal B, and the transfer destination terminal C, and the specific SIP server 1 is the calling SIP server F and the transfer destination SIP server G. However, the originating terminal A, the terminating terminal B, the transfer destination terminal C, the originating side SIP server F, and the transfer destination SIP server G may be any terminal 3 or SIP server 1, and the same processing is performed. .

DESCRIPTION OF SYMBOLS 1 SIP server 2 Relay server 3 Terminal 11 Subscriber information database 12 Call processing control part 20 External database apparatus 201 Mirror database 202 Mirror database management part A Originating side terminal B Destination side terminal C Destination side D Destination side SIP server E Relay server F Originating SIP server G Forwarding destination SIP server

Claims (4)

A telephone system comprising a plurality of SIP servers, an external database device, and a relay server,
Each SIP server is
Each subscriber includes a subscriber telephone number which is the subscriber's telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination. A subscriber information database in which subscriber information is stored;
The external database device is
A mirror database that is a duplicate of each of the subscriber information databases;
A mirror database management unit that turns on all affected persons flags of the mirror database generated from the subscriber information database of the SIP server when communication with any of the SIP servers is not possible,
The relay server is
If a call establishment request arrives, try to communicate with the SIP server corresponding to the destination of the call establishment request, and if communication is not possible, connect to the external database device and generate from the subscriber information database of the SIP server The subscriber information including the subscriber telephone number that matches the telephone number of the transmission destination of the call establishment request is searched from the mirror database, and the victim flag and the busy transfer flag in the subscriber information are both turned on. If the victim flag and the busy transfer flag are both on, the telephone system is characterized in that the destination of the call establishment request is rewritten based on the transfer destination information in the subscriber information. A telephone system comprising a plurality of SIP servers and an external database device,
Each SIP server is
Each subscriber includes a subscriber telephone number which is the subscriber's telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination. A subscriber information database in which subscriber information is stored;
The external database device is
A mirror database that is a duplicate of each of the subscriber information databases;
A mirror database management unit that turns on all affected persons flags of the mirror database generated from the subscriber information database of the SIP server when communication with any of the SIP servers is not possible,
When a call establishment request arrives, the call processing control unit of each SIP server obtains subscriber information from the subscriber information database, and the transmission destination of the call establishment request is set to the subscriber telephone number in the subscriber information. If they do not match, connect to the external database device and match the telephone number of the call establishment request destination from the mirror database generated from the subscriber information database of the SIP server corresponding to the destination of the call establishment request. The subscriber information including the subscriber telephone number to be searched is searched, it is determined whether both the victim flag and the busy transfer flag in the subscriber information are on, and if both the victim flag and the busy transfer flag are on, A telephone system characterized by rewriting the transmission destination of the call establishment request based on transfer destination information in the subscriber information. An operation method of a telephone system comprising a plurality of SIP servers, an external database device, and a relay server,
The SIP server
Each subscriber includes a subscriber telephone number which is the subscriber's telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination. A subscriber information database in which subscriber information is stored;
The external database device is
A mirror database that is a duplicate of each subscriber information database;
The operation method is as follows:
The mirror database management unit of the external database device turning on all the victim flags of the mirror database generated from the subscriber information database of the SIP server when communication with any of the SIP servers is not possible; ,
If the relay server receives a call establishment request, the relay server attempts to communicate with the SIP server corresponding to the transmission destination of the call establishment request;
When the relay server cannot communicate with the SIP server, connecting to the external database device;
The relay server searching subscriber information including a subscriber telephone number that matches a telephone number of a transmission destination of the call establishment request from a mirror database generated from a subscriber information database of the SIP server;
The relay server determining whether both the affected person flag and the busy transfer flag in the subscriber information are on;
The relay server comprises a step of rewriting a transmission destination of the call establishment request based on transfer destination information in the subscriber information when both the victim flag and the busy transfer flag are on. How the system works. A method of operating a telephone system comprising a plurality of SIP servers and an external database device,
Each SIP server is
Each subscriber includes a subscriber telephone number which is the subscriber's telephone number, a busy transfer flag indicating whether or not busy transfer is necessary, a victim flag indicating whether or not there is a disaster, and transfer destination information indicating a transfer destination. A subscriber information database in which subscriber information is stored;
The external database device is
A mirror database that is a duplicate of each subscriber information database;
The operation method is as follows:
The mirror database management unit of the external database device turning on all the victim flags of the mirror database generated from the subscriber information database of the SIP server when communication with any of the SIP servers is not possible; ,
The call processing control unit of any of the SIP servers obtains subscriber information from the subscriber information database if a call establishment request arrives;
The call processing control unit, when the destination of the call establishment request does not match the subscriber telephone number in the subscriber information, connecting to the external database device;
The call processing control unit includes a subscriber telephone number that matches the destination telephone number of the call establishment request from the mirror database generated from the subscriber information database of the SIP server corresponding to the transmission destination of the call establishment request. Searching for subscriber information;
The call processing control unit determining whether both the affected person flag and the busy transfer flag in the subscriber information are on;
The call processing control unit comprises a step of rewriting the transmission destination of the call establishment request based on the transfer destination information in the subscriber information when both the affected person flag and the busy transfer flag are on. How the phone system works.

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