JP2013243577A - Communication system and cash update method of enum cash device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce improper connection by reducing the number of times of connection with an ENUM server, and updating the information of an ENUM cash timely, while reducing the load of the ENUM server.SOLUTION: Upon receiving a connection request message including the call destination information from a terminal 10a on the origination side, an SIP server 20a inquires the connection destination information by transmitting the connection destination information request message to an ENUM cash device 30a storing the connection destination information corresponding to the called party information, and tries call connection with a called party SIP server 20b indicated by the connection destination information. When a determination is made that the call connection based on the connection destination information is not established and not indicating a correct connection destination, the SIP server 20a transmits the connection destination information re-request message to the ENUM cash device 30a. Upon receiving the connection destination information re-request message, the ENUM cash device 30a acquires the updated destination information from an ENUM server 40, and updates the cash data.

Description

  The present invention relates to a communication system to which IMS (IP Multimedia Subsystem) is applied, and particularly to a method for updating cache data of an ENUM cache device.

  In recent years, communication systems using IMS have become widespread. IMS integrates public communication services such as a fixed telephone network and a mobile communication network with IP (Internet Protocol) technology and SIP (Session Initiation Protocol) used in VoIP (Voice over Internet Protocol) terminals. The service is realized.

  Further, in a communication system using SIP, routing for realizing mutual communication between terminals is defined by 3GPP (3rd Generation Partnership Project) using ENUM (Telephone Number Mapping) (for example, Non-Patent Document 1 and Non-Patent Document 2).

  ENUM is defined by IETF (Internet Engineering Task Force) RFC3761 as a system that responds to inquiries by telephone number by using the DNS (Domain Name System) as the connection destination operator or the connection destination node name. ing. In routing using this ENUM, the SIP server installed in the telecommunications carrier's network is connected to the terminal identifier (telephone number, etc.) of the terminal to be connected (for example, the connected operator or the connection This is performed based on the information of the connection destination notified from the ENUM server.

  In the routing according to Non-Patent Document 1 and Non-Patent Document 2, the SIP server must make an inquiry (access to the ENUM server) to the ENUM server every time it receives a connection request from the terminal that it accommodates to another terminal. I must. However, since there are a plurality of communication carriers and a plurality of SIP servers are installed in the network of the communication carriers, the number of terminals accommodated by the SIP servers is enormous. When the SIP server accesses the ENUM server each time these terminals make a call, the load on the ENUM server increases. When the load on the ENUM server increases, the response time for an inquiry from the SIP server becomes longer, or in the worst case, the ENUM server cannot respond, resulting in an increase in connection delay between terminals or a connection failure.

  It is also assumed that the operator managing the ENUM requests a charge (access charge) for access to the ENUM server, and the telecommunications carrier increases its cost burden by increasing the number of accesses to the ENUM server. Become.

  By the way, DNS has a mechanism called a cache in which information once inquired to the DNS server is accumulated on the client side for a certain period. This cache mechanism is widely used to reduce the load of access to the DNS server in Web (World Wide Web) access using HTTP (HyperText Transfer Protocol) on the Internet. Various techniques for applying this cache mechanism to ENUM have been considered (see, for example, Patent Document 1).

“IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP) (Release 11)”, 3GPP, TS 24.229 V11.2.1, Feb 2012 "IR67-DNS Guidelines for Operators", GSMA, IR.67 vs4.1, March 2010

JP 2007-243564 A

  By the way, in a communication system using ENUM, for example, transfer of a server of a communication carrier or transfer of a terminal between communication carriers may occur. In particular, due to number portability, the transfer of terminals between telecommunications carriers has become common in recent years. When the server or terminal is transferred, the ENUM server information is changed to the latest information, but the ENUM cache information already stored on the client side is accessed by the ENUM cache device including the ENUM cache by accessing the ENUM server. Unless it is acquired, it will not be updated to the latest information.

  The period for storing ENUM cache information is set based on a response from the ENUM server in response to an inquiry from the client. In order to reduce the number of accesses to the ENUM server, the valid period of the ENUM cache information may be set longer. However, if the ENUM cache information valid period is set to be long, even if there is a server or terminal transfer within the valid period and the ENUM server information is changed, the connection is made based on the old ENUM cache information. There is a problem that the period of time when the connection destination is erroneously connected to the previous connection destination becomes long, and the connection destination before the change is erroneously connected many times until the ENUM cache is updated.

  In the case of transfer of a Web server using HTTP, it is possible to sufficiently shorten the erroneous connection time to the connection destination before the change by shortening the valid period of the cache in advance on the business side. However, since the terminal transfer between communication carriers is triggered by the user using the terminal, it cannot be predicted by the operator. For this reason, the valid period of the cache cannot be changed in advance, and the erroneous connection time cannot be sufficiently shortened.

  The present invention has been made in view of such a background. The present invention reduces the number of connections to the ENUM server, reduces the load on the ENUM server, and updates the information in the ENUM cache in a timely manner, thereby reducing misconnections. It is an object of the present invention to provide a communication system and a cache updating method for an ENUM cache device.

  In order to solve the above-described problem, the invention according to claim 1 is related to a SIP server installed in each telecommunications carrier network and accommodating at least one terminal, and a terminal identifier for identifying the terminal. Information of an ENUM server having a connection destination information table in which connection destination information for connecting to a SIP server that accommodates the terminal is registered, and information of a connection destination information table that is installed in each communication carrier network and that the ENUM server has An ENUM cache device having a cache function for acquiring and holding the call, and a SIP server on the calling side that has received a connection request message including destination information that is a terminal identifier of the terminal on the called side from a terminal accommodated by itself, Before the ENUM cache device is inquired about the connection destination information of the SIP server on the receiving side that accommodates the terminal indicated by the destination information. A communication system for connecting to a terminating SIP server and performing mutual communication between terminals, wherein the originating SIP server associates with a terminal identifier indicated by the destination information attached to the received connection request message The connection destination information is acquired from the ENUM cache device, the destination information indicated by the acquired connection destination information is notified to the SIP server on the receiving side, and the destination information is indicated by the SIP server on the receiving side. Control for re-inquiring the ENUM cache device for the connection destination information associated with the terminal identifier indicated by the destination information attached to the received connection request message when receiving a notification that the terminal is not accommodated. A terminal identifier for identifying the terminal accommodated by the SIP server on the receiving side is registered. A storage unit that stores a terminal information table and a terminal indicated by the destination information notified from the SIP server on the calling side are searched for in the accommodation terminal information table. The terminal indicated by the destination information is not registered in the accommodation terminal information table, a control unit that transmits a notification that the terminal is not contained to the originating SIP server, and the ENUM cache device includes: A storage unit storing a connection destination information cache table for registering connection destination information for connecting to a SIP server that accommodates the terminal in association with a terminal identifier for identifying the terminal; and When an inquiry is made again about the connection destination information associated with the terminal identifier indicated by the destination information, it is related to the terminal identifier indicated by the destination information. And a control unit that acquires the attached connection destination information from the ENUM server and registers the acquired connection destination information in the connection destination information cache table in association with the terminal identifier. .

  According to a second aspect of the present invention, there is provided a SIP server that is installed in each carrier network and accommodates at least one terminal, and a SIP server that accommodates the terminal in association with a terminal identifier for identifying the terminal. An ENUM server having a connection destination information table in which connection destination information for connection is registered, and a cache function that is installed in each communication carrier network and acquires and holds information of the connection destination information table of the ENUM server And a SIP server on the caller side that has received a connection request message including the callee information that is the terminal identifier of the callee terminal from the terminal accommodated by the ENUM cache device. Queries the ENUM cache device for connection destination information of the incoming call side SIP server and connects to the incoming call side SIP server. A communication system for performing mutual communication between terminals, wherein the SIP server on the calling side includes the destination information attached to the received connection request message and is associated with a terminal identifier indicated by the destination information A first connection destination information request message creating unit for creating a first connection destination information request message for requesting the connection destination information and transmitting the first connection destination information request message to the ENUM cache device; and a first connection destination information including the connection destination information from the ENUM cache device. When the connection destination information response message of 1 is received, a connection request message including the destination information is created and transmitted to the SIP server on the receiving side indicated by the connection destination information attached to the first connection destination information response message And a connection response message indicating that the terminal is not accommodated from the SIP server on the receiving side, A connection destination information rerequest message including the destination information attached to the continuation request message is created and transmitted to the ENUM cache device, and a connection destination information rerequest response from the ENUM cache device When the message is received, a connection re-request message including the destination information attached to the connection request message is created, and the destination-side SIP server indicated by the connection destination information attached to the connection destination information re-request response message A connection re-request message creating unit for transmitting to the storage side, and a storage unit for storing a terminal information table in which a terminal identifier for identifying a terminal accommodated by the SIP server is stored. When the connection request message or the connection re-request message is received from the calling-side SIP server, the connection request message is received. The terminal indicated by the destination information attached to the request message or the connection re-request message is searched for whether or not the terminal indicated by the destination information is registered in the accommodation terminal information table. If the terminal is not registered in the terminal information table, the terminal is not accommodated if the terminal is not accommodated, and the terminal search unit determines that the terminal is not accommodated. A connection response message creating unit that creates a connection response message indicating the terminal and transmits the connection response message to the SIP server on the caller side, and the ENUM cache device accommodates the terminal in association with a terminal identifier for identifying the terminal A storage unit for storing a connection destination information cache table for registering connection destination information for connection to the SIP server, and the originating SIP server The destination information attached to the first connection destination information request message received is extracted, and connection destination information is registered in the connection destination information cache table in association with the terminal identifier indicated by the extracted destination information. A connection destination information cache table search unit for searching whether or not the connection destination information cache table, and a second connection destination information request message including destination information attached to the connection destination information re-request message received from the SIP server on the caller side. A second connection destination information request message creation unit that creates and transmits to the ENUM server, and extracts connection destination information attached to the second connection destination information response message received from the ENUM server, and extracts the connection The destination information is registered in the connection destination information cache table in association with the destination information included in the second connection destination information request message. When the connection destination information cache table update unit and the connection destination information cache table search unit can search the connection destination information associated with the terminal identifier indicated by the extracted destination information from the connection destination information cache table, the search The first connection destination information response message including the connection destination information is generated, and the first connection destination information response message creating unit that transmits the first connection destination information response message to the SIP server on the transmission side is received. When the second connection destination information request message is transmitted, the second connection destination information response message is received from the ENUM server, and the connection destination information attached to the second connection destination information response message is received. The connection destination information re-request response message including the connection destination information re-request response message is transmitted to the SIP server on the caller side. A storage unit for storing the connection destination information table, and the destination information attached to the second connection destination information request message received from the ENUM cache device. A connection destination search unit that extracts and acquires connection destination information registered in the connection destination information table in association with the terminal identifier indicated by the extracted destination information; and the connection destination information acquired by the connection destination search unit A communication system comprising: a second connection destination information response message generation unit that generates the second connection destination information response message and transmits the second connection destination information response message to the ENUM cache device.

  According to a third aspect of the present invention, there is provided a SIP server that is installed in each carrier network and accommodates at least one terminal, and a SIP server that accommodates the terminal in association with a terminal identifier for identifying the terminal. An ENUM server having a connection destination information table in which connection destination information for connection is registered, and a cache function that is installed in each communication carrier network and acquires and holds information of the connection destination information table of the ENUM server And a SIP server on the caller side that has received a connection request message including the callee information that is the terminal identifier of the callee terminal from the terminal accommodated by the ENUM cache device. Queries the ENUM cache device for connection destination information of the incoming call side SIP server and connects to the incoming call side SIP server. A cache updating method for an ENUM cache device in a communication system for performing mutual communication between terminals, wherein the SIP server stores a accommodated terminal information table in which a terminal identifier for identifying a terminal accommodated by itself is registered. A storage unit, wherein the ENUM cache device stores a connection destination information cache table for registering connection destination information for connection to a SIP server accommodating the terminal in association with a terminal identifier for identifying the terminal; The ENUM server includes a storage unit for storing the connection destination information table, and the SIP server on the calling side includes the destination information attached to the connection request message, and the destination A first connection destination information request message for requesting the connection destination information associated with the terminal identifier indicated by the information Creating and transmitting to the ENUM cache device, the ENUM cache device extracting the destination information attached to the first connection destination information request message received from the SIP server on the caller side, and A step of searching whether or not connection destination information is registered in association with a terminal identifier indicated by the extracted destination information in the connection destination information cache table; and the ENUM cache device extracts the connection destination information from the connection destination information cache table When the connection destination information associated with the terminal identifier indicated by the received destination information can be searched, a first connection destination information response message including the searched connection destination information is created and transmitted to the SIP server on the caller side And the SIP server on the calling side includes the connection destination information from the ENUM cache device. When the first connection destination information response message is received, a connection request message including the destination information is created, and the destination-side SIP server indicated by the connection destination information attached to the first connection destination information response message And the SIP server on the receiving side searches whether the terminal indicated by the destination information attached to the connection request message is registered in the accommodation terminal information table, and the result of the search When the terminal indicated by the destination information is not registered in the accommodation terminal information table, determining that the terminal is not accommodated by the terminal, and that the SIP server on the destination side If the determination is that the terminal is not accommodated, a connection response message indicating that the terminal is not accommodated is created and transmitted to the SIP server on the originating side; When the server receives a connection response message indicating that the terminal is not accommodated from the SIP server on the receiving side, it creates a connection destination information re-request message including the destination information attached to the connection request message, and the ENUM cache device The ENUM cache device creates a second connection destination information request message including destination information attached to the connection destination information re-request message received from the SIP server on the caller side, and Transmitting to the ENUM server, and the ENUM server extracts the destination information attached to the second connection destination information request message received from the ENUM cache device, and the terminal indicated by the extracted destination information The connection destination information registered in the connection destination information table in association with the identifier is acquired, and the acquired Creating a second connection destination information response message including connection destination information and transmitting the second connection destination information response message to the ENUM cache device; and attaching the ENUM cache device to the second connection destination information response message received from the ENUM server. Extracting the connected connection destination information, and registering the extracted connection destination information in the connection destination information cache table in association with the destination information included in the second connection destination information request message. The cache update method of the ENUM cache device is characterized by the above.

  In this way, the SIP server on the transmission side that has received the connection request message with the destination information attached from the terminal that it accommodates itself connects to the ENUM cache device that stores the connection destination information corresponding to the destination information. An information request message is transmitted to inquire about connection destination information, and a connection request message is transmitted to the SIP server on the receiving side indicated in the connection destination information. Then, if the SIP server on the receiving side determines that the terminal indicated in the destination information is not accommodated, it transmits a connection response message that does not contain the terminal to the SIP server on the originating side. When the SIP server on the calling side receives a connection response message that does not contain a terminal, it transmits a connection destination information rerequest message to the ENUM cache device. Upon receiving the connection destination information re-request message, the ENUM cache device transmits a connection destination request message to the ENUM server, acquires the changed connection destination information, and registers it in the connection destination information cache table.

  By doing so, there is no need to set the valid period of the cache data in the ENUM cache device, so the number of times the ENUM server is accessed periodically every time the valid period elapses, and the load on the ENUM server is reduced. be able to. Furthermore, when access to the ENUM server is charged, the connection to the ENUM server only needs to be made when connecting to the terminal for the first time after the connection destination information regarding the terminal on the called side is changed. Access charge can be minimized.

  According to the present invention, a communication system and an ENUM cache apparatus cache update method that can update ENUM cache information in a timely manner and reduce erroneous connections while reducing the number of connections to the ENUM server and reducing the load on the ENUM server. Can be provided.

It is a figure which shows the outline | summary of the whole structure and process of the communication system which concern on this embodiment. It is a functional block diagram which shows the structural example of the SIP server which concerns on this embodiment. It is a functional block diagram which shows the structural example of the ENUM cache apparatus which concerns on this embodiment. It is a figure which shows the example of a data structure of the connection destination information cache table which concerns on this embodiment. It is a functional block diagram which shows the structural example of the ENUM server which concerns on this embodiment. It is a figure for demonstrating the flow of the 1st process of the communication system which concerns on this embodiment. It is a figure for demonstrating the flow of the 2nd process of the communication system which concerns on this embodiment. It is a sequence diagram which shows the flow of the 3rd process of the communication system which concerns on this embodiment.

  Next, a cache update method for the communication system 100 and the ENUM cache device 30 in a mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described.

≪Overview≫
First, an overview of the communication system 100 according to the present embodiment will be described.

<System configuration>
FIG. 1 is a diagram illustrating an overall configuration and processing overview of a communication system 100 according to the present embodiment.
A communication system 100 according to the present embodiment is a communication system to which IMS is applied. As shown in FIG. 1, as shown in FIG. A calling party network 1a ", a called party network 1 is called a" destination network 1b "), and an ENUM server 40 that is accessible from each network 1.
Each carrier network 1 stores an ENUM cache device 30 that stores information (ENUM cache) in which the SIP server 20 that accommodates the plurality of terminals 10 and the destination information acquired from the ENUM server 40 are associated with the connection destination information. With. The ENUM cache device 30 is connected to the SIP server 20 and the ENUM server 40. The SIP server 20 connects a SIP server 20a belonging to the originating provider network 1a and a SIP server 20b (20b-1, 20b-2) belonging to the terminating provider network 1b via a gateway device (not shown). Is done. The terminal 10 is a terminal device compatible with VoIP, for example, an IP telephone.

  The ENUM server 40 includes a connection destination information table 430 in which the destination information and the connection destination information are associated with each other, and the destination information (for example, the destination telephone number) from the ENUM cache device 30 of each carrier network 1 is stored. In response to the attached connection destination information request message, the connection destination information table 430 is referred to, and the connection destination information corresponding to the destination information (for example, the IP address of the SIP server that accommodates the terminal 10 on the receiving side) is ENUM. It is transmitted to the cache device 30 as a connection destination information response message. In this connection destination information table 430, the latest connection destination information accompanying the transfer of a server or a terminal is registered.

The SIP server 20 receives the connection request message with the destination information (for example, the destination telephone number) from the terminal 10 accommodated by itself, and the connection destination information corresponding to the destination information received by the ENUM cache device 30 Call connection processing is performed by inquiring.
In addition, when the call connection based on the connection destination information acquired from the ENUM cache device 30 fails, the SIP server 20 determines that the information stored in the ENUM cache is old and does not indicate a correct connection destination. Then, the SIP server 20 transmits to the ENUM cache device 30 a connection destination information re-request message for requesting the changed connection destination information, and the changed connection destination information acquired by the ENUM cache device 30 from the ENUM server 40. To establish a call connection.

The ENUM cache device 30 stores, in the connection destination information cache table 330, information (ENUM cache) obtained by associating destination information and connection destination information acquired from the ENUM server 40 in response to an inquiry from the SIP server.
In addition, when the ENUM cache device 30 receives the connection destination information re-request message for requesting the changed connection destination information from the SIP server 20, the ENUM cache device 30 inquires the ENUM server 40 and updates the connection destination information in the connection destination information cache table 330. The connection destination information re-request response message with the updated connection destination information is transmitted to the SIP server 20.
In the following description, the terminal 10 on the originating provider network 1a is referred to as a terminal 10a, the ENUM cache device 30 is referred to as an ENUM cache device 30a, the terminal 10 on the destination provider network 1b side is referred to as a terminal 10b, and the ENUM cache device 30 is referred to as an ENUM cache. The apparatus 30b will be described.

<Process overview>
Next, an outline of processing of the communication system 100 will be described with reference to FIG.
Here, a description will be given assuming that the SIP server 20b that accommodates the terminal 10b in the called carrier network 1b is changed from “SIP server (B)” to “SIP server (C)”.
As shown in FIG. 1, the transfer of the terminal 10 b is already reflected in the connection destination information table 430 of the ENUM server 40, and “SIP server (C) IP address” is stored as the new connection destination information after the change. It shall be.
On the other hand, it is assumed that the connection destination information cache table 330 of the ENUM cache device 30a stores information on the ENUM cache before the transfer of the terminal 10b shown in the connection destination information cache table 330 (330b). Specifically, in the connection destination information cache table 330b, the telephone number “042-567-0001” of the terminal 10b on the receiving side is stored as the destination information, and the terminal 10b is accommodated in the connection destination information before the transfer. The IP address of the SIP server 20b-1 ("SIP server 20 (B) IP address" in the figure) is stored.

  First, in order to request connection with the terminal 10b, the terminal 10a transmits a connection request message including call destination information (such as the telephone number of the callee terminal 10b) to the SIP server 20a (step S1). The SIP server 20a creates a connection destination information request message for requesting acquisition of connection destination information corresponding to the destination information attached to the connection request message, and transmits the created connection destination information request message to the ENUM cache device 30a. (Step S2).

  The ENUM cache device 30a searches the connection destination information cache table 330b based on the destination information attached to the connection destination information request message, and acquires the connection destination information. Here, “SIP server (B) IP address” is acquired as the connection destination information. The ENUM cache device 30a creates a connection destination information response message including the acquired connection destination information, and transmits it to the SIP server 20a (step S3).

  The SIP server 20a extracts the connection destination information attached to the connection destination information response message, and sends a connection request message to the SIP server 20b-1 indicated by “SIP server (B) IP address” as the extracted connection destination information. Is transmitted (step S4).

  The SIP server 20b-1 determines whether or not it itself accommodates the terminal (in this case, the terminal 10b) indicated by the destination information attached to the connection request message. Here, the SIP server 20b-1 accommodates the terminal 10b before the relocation, but currently does not accommodate the terminal 10b. Therefore, the SIP server 20b-1 transmits a connection response message indicating that the terminal 10b is not accommodated (a connection response message not accommodated in the terminal) to the SIP server 20a (step S5).

  When the SIP server 20a receives a connection response message that does not contain a terminal, it recognizes that the call cannot be connected. Therefore, the SIP server 20a creates a connection destination information re-request message for requesting the changed connection destination information after the transfer to the ENUM cache device 30a, and transmits it to the ENUM cache device 30a (step S6).

  When the ENUM cache device 30a receives the connection destination information rerequest message, the ENUM cache device 30a transmits a connection destination information request message to the ENUM server 40 (step S7), and the connection with the new changed connection destination information is added from the ENUM server 40. A destination information response message is received (step S8). Here, the ENUM cache device 30a receives “SIP server (C) IP address” as the connection destination information after the change.

Subsequently, the ENUM cache device 30a extracts the connection destination information attached to the connection destination information response message, and updates the connection destination information cache table 330 (step S9).
Here, as shown in the connection destination information cache table 330 (330c) of FIG. 1, the connection destination information corresponding to the terminal 10b is changed from “SIP server (B) IP address” to “SIP server (C)”. Update to "IP address". As a result, the connection destination information cache table 330 of the ENUM cache device 30a has the latest information regarding the terminal 10b, that is, the connection destination information after the same change as that of the ENUM server 40.

  Next, the ENUM cache device 30a creates a connection destination information re-request response message including the updated connection destination information, and transmits it to the SIP server 20a (step S10).

  The SIP server 20a extracts the connection destination information attached to the connection destination information rerequest response message, and connects to the SIP server 20b-2 indicated by “SIP server (C) IP address” as the extracted connection destination information. A re-request message is transmitted (step S11).

  The SIP server 20b-2 determines that the terminal (here, the terminal 10b) indicated by the destination information attached to the connection rerequest message is accommodated, and transmits a call connection request message to the terminal 10b ( Step S12). Then, the SIP server 20b-2 receives a call connection response message indicating that a connection request is accepted from the terminal 10b (step S13).

  When receiving the call connection response message from the terminal 10b, the SIP server 20b-2 transmits a connection response message indicating that the call connection is possible to the SIP server 20a (step S14).

  The SIP server 20a that has received the connection response message transmits the connection request response message to the terminal 10a (step S15), thereby enabling communication between the terminal 10a and the terminal 10b.

As described above, in the communication system 100 according to the present embodiment, the information (ENUM cache) associated with the destination information and the connection destination information stored in the ENUM cache device 30 indicates the current correct connection destination information. Whether or not the call connection processing has succeeded is determined. Only when the call connection fails, the new connection destination information after the change is acquired from the ENUM server 40, assuming that the connection destination information is not correct. Update the ENUM cache.
In this way, it is not necessary to set the valid period of the information in the ENUM cache, and the ENUM server 40 is accessed only when the call connection fails, so that the ENUM is not increased without increasing the load on the ENUM server 40. It is possible to update the cache information and perform call connection.

≪Configuration of each device≫
Below, the specific structure of each apparatus which comprises the communication system 100 which concerns on this embodiment is demonstrated.

<SIP server>
FIG. 2 is a functional block diagram illustrating a configuration example of the SIP server 20 according to the present embodiment.
The SIP server 20 according to the present embodiment changes to the ENUM cache device 30 when call connection based on the information (ENUM cache) that associates the destination information and the connection destination information stored in the ENUM cache device 30 fails. A connection destination information re-request message for requesting subsequent connection destination information is transmitted, and the ENUM cache device 30 performs call connection processing based on the changed connection destination information acquired from the ENUM server 40.
The SIP server 20 includes a communication unit 21, a control unit 22, a storage unit 23, and a memory unit 24.

  The communication unit 21 includes a communication interface that transmits and receives information to and from the terminal 10, the ENUM cache device 30, the SIP server 20 of another provider network 1, and the like. When the communication unit 21 receives a message or the like from an external device, the communication unit 21 hands it over to a message analysis unit 221 described later in the control unit 22. In addition, a message or the like created in the control unit 22 is transmitted to an external device.

  The control unit 22 controls all processes executed by the SIP server 20, and includes a message analysis unit 221, a connection destination information request message creation unit (first connection destination information request message creation unit) 222, and a connection request message creation unit. 223, a connection destination information rerequest message creation unit 224, a connection rerequest message creation unit 225, a connection request response message creation unit 226, an accommodation terminal search unit 227, a connection response message creation unit 228, and a call connection request And a message creation unit 229.

  The message analysis unit 221 analyzes a message received via the communication unit 21 and performs each component according to the message (connection destination information request message creation unit 222 to call connection request message creation). Part 229).

  The connection destination information request message creation unit (first connection destination information request message creation unit) 222 receives destination information (such as the telephone number of the terminal 10b as the destination) from the terminal 10 via the message analysis unit 221. When the received connection request message is received, a connection destination information request message (first connection destination information request message) requesting connection destination information (such as the IP address of the destination SIP server) corresponding to the destination information is created. To do. Then, the connection destination information request message creation unit 222 transmits a connection destination information request message including the destination information to the ENUM cache device 30 via the communication unit 21.

  When the connection request message creation unit 223 receives the connection destination information response message from the ENUM cache device 30 via the message analysis unit 221, the connection request message creation unit 223 extracts the connection destination information attached to the connection destination information response message, A connection request message including information (the telephone number of the terminal 10b that is the destination) is created. Then, the connection request message creating unit 223 transmits the created connection request message to the connection destination (the incoming SIP server 20 (20b-1) or the like) indicated by the connection destination information.

  The connection destination information re-request message creation unit 224 receives the SIP server 20 (20b-1) from the incoming call side SIP server 20 (20b-1) or the like via the message analysis unit 221. If a connection response message indicating that the terminal is not accommodated is received, a connection destination information rerequest message for requesting the connection destination information after the change is generated. Then, the connection destination information rerequest message creation unit 224 transmits a connection destination information rerequest message including the destination information to the ENUM cache device 30 via the communication unit 21.

  When the connection rerequest message creation unit 225 receives the connection destination information rerequest response message from the ENUM cache device 30 via the message analysis unit 221, the connection rerequest message creation unit 225 changes the connection attached to the connection destination information rerequest response message. The destination information is extracted, and a connection re-request message including the destination information (the telephone number of the terminal 10b as the destination) is created. Then, the connection rerequest message creation unit 225 transmits the created connection rerequest message to the connection destination (such as the destination SIP server 20b-2) indicated by the changed connection destination information.

  Via the message analysis unit 221, the connection request response message creating unit 226 sends the terminal 10b indicated in the destination information from the connection destination (such as the incoming SIP server 20b-2) indicated in the changed connection destination information. When a connection response message indicating that the call connection is possible is received, a connection request response message indicating that the call connection processing with the destination is completed is created. Then, the connection request response message creating unit 226 transmits the created connection request response message to the terminal 10a.

  Next, the accommodation terminal search unit 227, the connection response message creation unit 228, and the call connection request message creation unit 229 will be described. The connection destination information request message creation unit 222, the connection request message creation unit 223, the connection destination information rerequest message creation unit 224, the connection rerequest message creation unit 225, and the connection request response message creation unit 226 described above are configured by the SIP server 20. It is a component that functions when the SIP server 20a belongs to the originating side operator network 1a. On the other hand, the accommodation terminal search unit 227, the connection response message creation unit 228, and the call connection request message creation unit 229 are components that function when the SIP server 20 is the SIP server 20b belonging to the called carrier network 1b. It is.

When receiving the connection request message or the connection re-request message from the caller-side SIP server 20a via the message analysis unit 221, the accommodation terminal search unit 227 receives the destination information attached to the connection request message and the connection re-request message. To extract. Then, the accommodated terminal search unit 227 refers to the accommodated terminal information table 230 in the storage unit 23 and determines whether or not the SIP server 20b accommodates the terminal 10b indicated by the destination information.
If it is determined that the terminal 10b indicated in the destination information is not accommodated, the accommodation terminal search unit 227 outputs a processing instruction to the connection response message creation unit 228. On the other hand, if it is determined that the terminal 10b indicated in the destination information is accommodated, the accommodation terminal search unit 227 outputs a processing instruction to the call connection request message creation unit 229.

When the accommodated terminal search unit 227 determines that the terminal 10b indicated in the destination information is not accommodated, the connection response message creating unit 228 indicates that the terminal 10b is not accommodated (terminal not accommodated). Connection response message) is transmitted to the originating SIP server 20a.
Further, when receiving a call connection response message indicating that the connection request is accepted from the terminal 10b, the connection response message creating unit 228 transmits a connection response message indicating that the call connection is possible to the originating SIP server 20a. .

  When the accommodated terminal search unit 227 determines that the terminal 10b indicated by the destination information is accommodated, the call connection request message creating unit 229 transmits a call connection request message requesting call connection to the terminal 10b.

The storage unit 23 is configured by a storage medium such as a hard disk or a flash memory that can read and write data and can store stored data even when power is not supplied to the storage unit 23.
The storage unit 23 stores an accommodation terminal information table 230 in which information (hereinafter referred to as accommodation terminal information) for identifying the terminal 10 accommodated therein is registered. The accommodation terminal information table 230 is used when determining whether or not the terminal 10b indicated by the destination information attached to the connection request message is accommodated when the SIP server 20 functions as the receiving side. .
Information for identifying the terminal 10b includes a telephone number, E.I. Information obtained by reversing the 164 number and attaching “e164nwa.com” (hereinafter referred to as “ENUM number”) or the like is used. For example, “042-567-0001” and “+81425670001” are used for telephone numbers, and “1.0.0.0.7.6.5.2.4.1.8.e164nwa.com” is used for ENUM numbers.
In addition, registration of the accommodation terminal information in the accommodation terminal information table 230 shall be performed using the input means which is not shown in figure. Also, the registration format is unified with either a telephone number or an ENUM number.

  The memory unit 24 is configured by a primary storage device such as a RAM (Random Access Memory), and temporarily holds information necessary for processing by the control unit 22. Further, the memory unit 24 is configured by configuring the control unit 22 with a CPU (Central Processing Unit), and when the functions of the control unit 22 are realized by a program, a program stored in the storage unit 23, a CD-ROM, or the like. Used as an area to expand. In this case, the CPU reads out the program from the storage medium in which the program is stored, expands it in the memory unit 24, and executes the expanded program to realize each function of the control unit 22.

<ENUM cache device>
FIG. 3 is a functional block diagram showing a configuration example of the ENUM cache device 30 according to the present embodiment.
The ENUM cache device 30 according to the present embodiment includes a connection destination information cache table 330 and stores information (ENUM cache) in which the destination information acquired by inquiring the ENUM server 40 and the connection destination information are associated with each other. When the ENUM cache device 30 receives a connection destination information re-request message for requesting the changed connection destination information from the SIP server 20 (20a) that has failed in the call connection, the ENUM cache device 30 makes an inquiry to the ENUM server 40 again. Thus, the changed new connection destination information is acquired, and the connection destination information cache table 330 is updated.
The ENUM cache device 30 includes a communication unit 31, a control unit 32, a storage unit 33, and a memory unit 34.

  The communication unit 31 includes a communication interface that transmits / receives information to / from the SIP server 20, the ENUM server 40, and the like. When the communication unit 31 receives a message or the like from an external device, the communication unit 31 hands over the message to the message analysis unit 321 described later in the control unit 32. In addition, a message or the like created in the control unit 32 is transmitted to an external device.

  The control unit 32 is responsible for overall processing executed by the ENUM cache device 30, and includes a message analysis unit 321, a connection destination information cache table search unit 322, and a connection destination information response message creation unit (first connection destination information response message). Creation unit) 323, a connection destination information request message creation unit (second connection destination information request message creation unit) 324, a connection destination information cache table update unit 325, and a connection destination information rerequest response message creation unit 326. Consists of including.

  The message analysis unit 321 analyzes a message received via the communication unit 31 and performs each process according to the message (connection destination information cache table search unit creation unit 322 to connection destination information). The message is delivered to the cache table update unit 325).

When receiving the connection destination information request message from the SIP server 20 (20a) via the message analysis unit 321, the connection destination information cache table search unit 322 extracts the destination information attached to the connection destination information request message. . Then, the connection destination information cache table search unit 322 refers to the connection destination information cache table 330 in the storage unit 33 and searches for connection destination information corresponding to the destination information.
If the connection destination information corresponding to the destination information is registered, the connection destination information cache table search unit 322 extracts the connection destination information and instructs the connection destination information response message creation unit 323 to perform processing. Is output. On the other hand, the connection destination information cache table search unit 322 acquires the connection destination information from the ENUM server 40 in the connection destination information request message creation unit 324 when the connection destination information corresponding to the destination information is not registered. Process instructions are output.

FIG. 4 is a diagram illustrating a data configuration example of the connection destination information cache table 330 according to the present embodiment.
As shown in FIG. 4, the connection destination information cache table 330 stores connection destination information in association with the destination information.

  In the destination information, a terminal identifier for identifying the terminal 10b on the receiving side for the call request of the terminal 10a is registered. For example, a telephone number or an ENUM number is used as the terminal identifier. FIG. 4A shows an example of the connection destination information cache table 330 when a telephone number (for example, “042-567-0001”) is used as the destination information. FIG. 4B shows an example of the connection destination information cache table 330 when the ENUM number (for example, “1.0.0.0.7.6.5.2.4.1.8.e164num.net”) is used as the destination information. Show.

  In the connection destination information, identification information for identifying the SIP server 20 (20b) that accommodates the terminal 10b on the receiving side is registered in association with the destination information. As the connection destination information, for example, the IP address and node name of the SIP server 20 (20b), the business operator (connection destination circumstance person) in which the SIP server 20 (20b) is installed, and the like are used. 4A and 4B show an example in which the IP address of the SIP server 20 (20b) is registered as connection destination information.

  In addition, when using the node name of the SIP server 20 (20b) as a connection destination information, a provider (connection destination circumstance person) in which the SIP server 20 (20b) is installed, the SIP server 20a has a DNS function or the like. Thus, the IP address that can be connected to the SIP server 20b may be acquired from the node name of the SIP server 20b, the business operator (connection destination circumstance person) in which the SIP server 20b is installed, or the like.

Returning to FIG. 3, the connection destination information response message creation unit (first connection destination information response message creation unit) 323 uses the connection destination information cache table search unit 322 as the destination information attached to the connection destination information request message. When the corresponding connection destination information is registered in the connection destination information cache table 330 and the connection destination information can be extracted, a connection destination information response message (first connection destination information response message) including the connection destination information is displayed. create. Then, the connection destination information response message creating unit 323 transmits the created connection destination information response message to the SIP server 20 (20a) that has transmitted the connection destination information request message.
Further, the connection destination information response message creation unit 323, when the connection destination information cache table update unit 325 registers the connection destination information corresponding to the destination information received from the ENUM server 40 in the connection destination information cache table 330, A connection destination information response message including the registered connection destination information is created. Then, the connection destination information response message creating unit 323 transmits the created connection destination information response message to the SIP server 20 (20a) that has transmitted the connection destination information request message.

In the connection destination information request message creation unit (second connection destination information request message creation unit) 324, the connection destination information cache table search unit 322 registers the connection destination information corresponding to the destination information in the connection destination information cache table 330. If it is determined that the connection destination information does not exist, a connection destination information request message (second connection destination information request message) for requesting connection destination information corresponding to the destination information is created. Then, the connection destination information request message creation unit 324 transmits a connection destination information request message including the destination information to the ENUM server 40 via the communication unit 31.
When the connection destination information request message creation unit 324 receives the connection destination information rerequest message from the SIP server 20 (20a) via the message analysis unit 321, the destination information attached to the connection destination information rerequest message is received. Extract information. Then, the connection destination information request message creating unit 324 transmits a connection destination information request message including the extracted destination information and requesting the changed connection destination information to the ENUM server 40 via the communication unit 31.

When the connection destination information cache table update unit 325 receives the connection destination information response message from the ENUM server 40 via the message analysis unit 321, the connection destination information cache table update unit 325 extracts the connection destination information attached to the connection destination information response message. Then, the connection destination information cache table update unit 325 registers the extracted connection destination information in the connection destination information cache table 330 in association with the destination information. In addition, when the extracted connection destination information has already been registered, the connection destination information cache table updating unit 325 updates the registered connection destination information using the extracted connection destination information.
When the connection destination information is newly registered in the connection destination information cache table 330, the connection destination information cache table update unit 325 extracts the registered connection destination information, and the connection destination information response message creation unit 323 performs processing. Output instructions. In addition, when the connection destination information cache table update unit 325 updates the registered connection destination information to the connection destination information after the change, the connection destination information cache table update unit 325 extracts the updated connection destination information and sends a connection destination information rerequest response. Processing instructions are output to the message creation unit 326.

  The connection destination information rerequest response message creation unit 326 creates a connection destination information rerequest response message including the changed connection destination information acquired from the connection destination information cache table update unit 325. Then, the connection destination information rerequest response message creation unit 326 transmits the created connection destination information rerequest response message to the SIP server 20 (20a) that has transmitted the connection destination information rerequest message via the communication unit 31. .

The storage unit 33 is configured by a storage medium such as a hard disk or a flash memory that can read and write data and can store stored data even when power is not supplied to the storage unit 33.
The storage unit 33 stores the connection destination information cache table 330 (see FIG. 4) and the like.

  The memory unit 34 is configured by a primary storage device such as a RAM, and temporarily holds information necessary for the processing of the control unit 22. Further, the memory unit 34 is configured as an area for developing a program stored in the storage unit 33, a CD-ROM, or the like when the control unit 32 is configured by a CPU and each function of the control unit 32 is realized by a program. It is done. In this case, the CPU reads out the program from the storage medium in which the program is stored, expands it in the memory unit 34, and executes the expanded program to realize each function of the control unit 32.

<ENUM server>
FIG. 5 is a functional block diagram illustrating a configuration example of the ENUM server 40 according to the present embodiment.
The ENUM server 40 includes a communication unit 41, a control unit 42, a storage unit 43, and a memory unit 44.

  The communication unit 41 includes a communication interface that transmits and receives information to and from the SIP server 20 and the like. When the communication unit 41 receives a message or the like from an external device, the communication unit 41 passes the message to a message analysis unit 421 described later in the control unit 42. In addition, a message or the like created in the control unit 42 is transmitted to an external device.

  The control unit 42 controls all processes executed by the ENUM server 40, and includes a message analysis unit 421, a connection destination search unit 422, and a connection destination information response message creation unit (second connection destination information response message creation unit) 423. It is comprised including.

  The message analysis unit 421 analyzes the message received via the communication unit 41 and passes the message to the component (connection destination search unit 422) in the control unit 32 that performs processing according to the message.

When receiving the connection destination information request message from the ENUM cache device 30 (30a) via the message analysis unit 421, the connection destination search unit 422 extracts the destination information attached to the connection destination information request message. Then, the connection destination search unit 422 refers to the connection destination information table 430 in the storage unit 43 and searches for connection destination information corresponding to the destination information. The connection destination search unit 422 extracts connection destination information obtained as a result of searching the connection destination information table 430 and outputs a processing instruction to the connection destination information response message creation unit 423.
The data structure of the connection destination information table 430 is the same as that of the connection destination information cache table 330 of the ENUM cache device 30 shown in FIG. However, in the connection destination information table 430 of the ENUM server 40, all terminals 10 accommodated by the SIP server 20 of the managed operator network 1 are registered as the destination information. When the connection destination information corresponding to the information is changed, the latest information reflecting the change is stored.

  The connection destination information response message creation unit (second connection destination information response message creation unit) 423 is a connection destination information response message (second connection destination information response message) including the connection destination information extracted by the connection destination search unit 422. Create Then, the connection destination information response message creating unit 423 transmits the created connection destination information response message to the ENUM cache device 30 (30a) that has transmitted the connection destination information request message.

The storage unit 43 is configured by a storage medium such as a hard disk or a flash memory that can read and write data and can store stored data even when power is not supplied to the storage unit 43.
The storage unit 43 stores the connection destination information table 430 and the like described above.

  The memory unit 44 is configured by a primary storage device such as a RAM, and temporarily holds information necessary for processing by the control unit 42. Further, the memory unit 44 is configured as an area for developing a program stored in the storage unit 43, a CD-ROM, or the like when the control unit 42 is configured by a CPU and each function of the control unit 42 is realized by a program. It is done. In this case, the CPU reads out the program from the storage medium in which the program is stored, expands the program in the memory unit 44, and executes the expanded program to realize each function of the control unit 42.

≪Communication system processing≫
Next, processing of the communication system 100 according to the present embodiment will be described. The processing of the communication system 100 is divided into three. First, the first process is a process when connection destination information is not registered in the connection destination information cache table 330 of the ENUM cache device 30a in association with the destination information of the destination terminal 10b. The second process is a process when connection destination information associated with the destination information of the destination terminal 10b is registered in the connection destination information cache table 330 of the ENUM cache device 30a. In the third process, as described in the outline above, the connection destination information is registered in the connection destination information cache table 330 of the ENUM cache device 30a in association with the destination information of the destination terminal 10b. This is a process when the contents are old and do not match the connection destination information after the change.

<First processing>
FIG. 6 is a diagram for explaining a first processing flow of the communication system 100 according to the present embodiment.
In the first process, as an initial state, connection destination information corresponding to the destination information is not registered in the connection destination information cache table 330 of the ENUM cache device 30a (see “connection destination information cache table 330a” in FIG. 6). ). Therefore, the ENUM cache device 30a makes an inquiry to the ENUM server 40 to acquire connection destination information and registers it in the connection destination information cache table 330 (see “connection destination information cache table 330b” in FIG. 6). The process flow will be specifically described below.

  First, in order to request connection with the terminal 10b, the terminal 10a transmits a connection request message including the destination information (here, the telephone number “042-567-0001” of the terminal 10b on the receiving side) to the SIP server 20a. (Step S21). The connection destination information request message creating unit 222 of the SIP server 20a creates a connection destination information request message including the destination information attached to the connection request message, and transmits it to the ENUM cache device 30a (step S22).

  The connection destination information cache table search unit 322 of the ENUM cache device 30a connects the connection registered in the connection destination information cache table 330 based on the destination information (“042-567-0001”) attached to the connection destination information request message. Search for destination information. Here, the connection destination information associated with the destination information (“042-567-0001”) of the terminal 10b is not registered in the connection destination information cache table 330a. Therefore, the connection destination information request message creation unit 324 creates a connection destination information request message for requesting connection destination information corresponding to the destination information, and transmits it to the ENUM server 40 (step S23).

  The connection destination search unit 422 of the ENUM server 40 refers to the connection destination information table 430 based on the destination information attached to the connection destination information request message, and extracts the destination information corresponding to the destination information. Here, the connection destination search unit 422 extracts “SIP server (B) IP address” as the destination information associated with the destination information (“042-567-0001”). Then, the connection destination information response message creation unit 423 of the ENUM server 40 creates a connection destination information response message including the extracted destination information (“SIP server (B) IP address”), and transmits it to the ENUM cache device 30a. (Step S24).

  When the connection destination information cache table update unit 325 of the ENUM cache device 30a receives the connection destination information response message, the connection destination information cache table update unit 325 extracts the connection destination information and associates it with the destination information (“042-567-0001”). The connection destination information (“SIP server (B) IP address”) is registered in the cache table 330 (see step S25: “connection destination information cache table 330b” in FIG. 6). As a result, the connection destination information cache table 330 of the ENUM cache device 30a has the latest information regarding the terminal 10b, that is, the same information as the connection destination information table 430 of the ENUM server 40.

  Subsequently, the connection destination information response message creation unit 323 of the ENUM cache device 30 a creates a connection destination information response message including the connection destination information (“SIP server (B) IP address”) registered in the connection destination information cache table 330. Then, it is transmitted to the SIP server 20a (step S26).

  Next, when the connection request message creating unit 223 of the SIP server 20a receives the connection destination information response message from the ENUM cache device 30, the connection destination information (“SIP server (B)) attached to the connection destination information response message. IP address ") is extracted, and a connection request message including destination information (" 042-567-0001 ") is created. Then, the connection request message creating unit 223 sends the created connection request message to the connection destination (“SIP server 20b-1” on the called side) indicated by the connection destination information (“SIP server (B) IP address”). Transmit (step S27).

  The accommodated terminal search unit 227 of the SIP server 20b-1 determines whether or not it accommodates the terminal (in this case, the terminal 10b) indicated by the destination information ("042-567-0001") attached to the connection request message. Is determined with reference to the accommodation terminal information table 230. When the accommodation terminal search unit 227 determines that the terminal 10b is accommodated because the destination information ("042-567-0001") is registered in the accommodation terminal information table 230, the SIP server The call connection request message creating unit 229 of 20b-1 transmits a call connection request message to the terminal 10b (step S28). Then, the terminal 10b transmits a call connection response message indicating acceptance of the connection request to the SIP server 20b-1 (step S29).

  When receiving the call connection response message from the terminal 10b, the connection response message creating unit 228 of the SIP server 20b-1 transmits a connection response message indicating that the call connection is possible to the SIP server 20a (step S30).

  The connection request response message creating unit 226 of the SIP server 20a receives a connection response message indicating that call connection is possible, creates a connection request response message, and transmits it to the terminal 10a (step S31).

<Second processing>
FIG. 7 is a diagram for explaining a second processing flow of the communication system 100 according to the present embodiment.
In the second process, as a result of the first process (see FIG. 6), the telephone number “042-567-0001 is stored in the connection destination information cache table 330 (330b) of the ENUM cache device 30a as the destination information of the terminal 10b. ", And the IP address" SIP server (B) IP address "of the SIP server 20b-1 that accommodates the terminal 10b is registered as connection destination information associated with the destination information of the terminal 10b. .

  Here, similarly to the first process (step S21) shown in FIG. 6, since the terminal 10a requests connection with the terminal 10b, the destination information (here, the telephone number “ 042-567-0001 ") is transmitted to the SIP server 20a (step S41). As a result, the connection destination information request message creating unit 222 of the SIP server 20a performs the same process as in step S22 of FIG. 6 in the connection including the destination information (“042-567-0001”) attached to the connection request message. A destination information request message is created and transmitted to the ENUM cache device 30a (step S42).

  The connection destination information cache table search unit 322 of the ENUM cache device 30a connects the connection registered in the connection destination information cache table 330 based on the destination information (“042-567-0001”) attached to the connection destination information request message. Search for destination information. Here, connection destination information (“SIP server (B) IP address”) associated with the destination information (“042-567-0001”) of the terminal 10b is registered in the connection destination information cache table 330 (330b). Has been. The connection destination information response message creation unit 323 creates a connection destination information response message including connection destination information (“SIP server (B) IP address”) obtained as a result of the search by the connection destination information cache table search unit 322. The connection destination information request message is transmitted to the SIP server 20 (20a) that has transmitted the message (step S43).

  Subsequent steps S44 to S48 are the same as steps S27 to S31 described in FIG.

  In this way, in the communication system 100, the ENUM cache device 30 (30a) stores the connection destination information corresponding to the destination information of the terminal 10b acquired from the ENUM server 40 in the first process (see FIG. 6). By registering in the connection destination information cache table 330, there is no need to make an inquiry to the ENUM server 40 when the call connection process is executed again for the terminal 10b. Therefore, the load on the ENUM server 40 can be reduced.

<Third processing>
FIG. 8 is a sequence diagram showing a third processing flow of the communication system 100 according to the present embodiment. In the third process, connection destination information is registered in the connection destination information cache table 330 of the ENUM cache device 30a in association with the destination information of the destination terminal 10b, but the contents are old and the connection destination of the ENUM server 40 is connected. This is processing when the connection destination information after the change stored in the information table 430 does not match. The ENUM cache device 30 continues to store the connection destination information corresponding to the destination information acquired in the first process (see FIG. 6) in the connection destination information cache table, but the SIP server 20a fails to connect the call. Only when a connection destination information re-request message indicating that the connection has been received is transmitted to the ENUM server 40, a connection destination information request message for requesting connection destination information is transmitted to obtain new connection destination information after the change, The connection destination information cache table 330 is updated (see FIGS. 1 to 5 as appropriate).

Note that the sequence diagram of FIG. 8 is for explaining the processing of the communication system 100 shown in FIG. 1 in more detail. In FIG. 8, the same step numbers as in FIG. To do.
As shown in FIG. 1, the connection destination information table 430 of the ENUM server 40 stores “SIP server (C) IP address” as the new connection destination information after the change corresponding to the destination information of the terminal 10b. However, it is assumed that the “SIP server (B) IP address” of the connection destination information before the change is stored as it is in the connection destination information cache table 330 (330b) of the ENUM cache device 30a. Further, it is assumed that the destination information is stored in the ENUM number format shown in FIG. 4B in the connection destination information table 430 of the ENUM server 40 and the connection destination information cache table 330 of the ENUM cache device 30a.

  First, the terminal 10a transmits a connection request message (INVITE) including destination information (“+81425670001”) to the SIP server 20a in order to request a connection with the terminal 10b (step S1).

  When receiving the connection request message (INVITE), the connection destination information request message creating unit 222 of the SIP server 20 receives the destination information (“1.0.0.0.7.6.5.2.4.2.1.8.e164num.”) To be notified to the ENUM cache device 30a. A connection destination information request message (ENUM Query) including “net”) is generated and transmitted to the ENUM cache device 30a (step S2). Note that the connection destination information request message creating unit 222 creates the destination information by adding “e164num.net” to the telephone numbers attached to the connection request message in reverse order and separating them with dots.

  The connection destination information cache table search unit 322 of the ENUM cache device 30a receives the destination information (“1.0.0.0.7.6.5.2.4.2.1.8.e164num.net”) attached to the connection destination information request message (ENUM Query). Based on the above, the connection destination information in the connection destination information cache table 330 is searched. Here, connection destination information (“SIP server (B) IP address”) associated with the destination information of the terminal 10b is registered in the connection destination information cache table 330 (330b). The connection destination information response message creation unit 323 includes a connection destination information response message (ENUM Answer) including connection destination information (“SIP server (B) IP address”) obtained as a result of the search by the connection destination information cache table search unit 322. Is transmitted to the SIP server 20 (20a) that has transmitted the connection destination information request message (ENUM Query) (step S3).

  Next, when the connection request message creating unit 223 of the SIP server 20a receives the connection destination information response message (ENUM Answer) from the ENUM cache device 30a, the connection destination attached to the connection destination information response message (ENUM Answer). Information (“SIP server (B) IP address”) is extracted, and a connection request message (INVITE) including the destination information (“+81425670001”) is created. Then, the connection request message creating unit 223 sends the created connection request message (INVITE) to the connection destination (“SIP server 20b-1 on the destination side) indicated by the connection destination information (“ SIP server (B) IP address ”). ]) (Step S4).

  When receiving the connection request message (INVITE), the accommodation terminal search unit 227 of the SIP server 20b-1 indicates a terminal (here, a terminal) indicated by the destination information (“+81425670001”) attached to the connection request message (INVITE) It is determined with reference to the accommodation terminal information table 230 whether or not 10b) is accommodated. Here, the SIP server 20b-1 previously accommodated the terminal 10b, but has not accommodated the terminal 10b at present due to relocation. Therefore, the accommodation terminal search unit 227 determines that the terminal 10b is not accommodated.

Subsequently, the connection response message creating unit 228 of the SIP server 20b-1 creates a terminal unaccommodated connection response message (404 (INVITE)) indicating that it does not accommodate the terminal 10b indicated by the destination information. And transmitted to the SIP server 20a (step S5).
Specifically, the connection response message creation unit 228 of the SIP server 20 b-1 has a Reason Header value of “404 Not Found Message” with protocol = “Q.850”, protocol-cause = “cause = 1”, etc. Then, a connection response message (404 (INVITE)) for notifying that the SIP server 20b-1 does not accommodate the terminal 10b for which connection is requested is transmitted to the SIP server 20a.

When the message analysis unit 221 of the SIP server 20a receives the connection response message (404 (INVITE)) that is not accommodated in the terminal, the message analysis unit 221 recognizes that the call cannot be connected, and instructs the connection destination information rerequest message creation unit 224 to perform processing. The connection destination information rerequest message creation unit 224 creates a connection destination information rerequest message (ENUM Query) for requesting the changed connection destination information from the ENUM cache device 30a, and transmits it to the ENUM cache device 30a (step S6). ).
Specifically, the connection destination information re-request message creation unit 224 of the SIP server 20a includes the destination information “1.0.0.0.7.6.5.2.4.2.1.8.e164num.net” and is a re-request. “1.0.0.0.7.6.5.2.4.2.1.8.e164num.net.retry” including “retry” indicating the connection destination information is generated as a connection destination information re-request message (ENUM Query) and transmitted to the ENUM cache device 30a. .

  When the message analysis unit 321 of the ENUM cache device 30a receives the connection destination information rerequest message (ENUM Query), the message analysis unit 321 recognizes that the call cannot be connected based on “retry” attached to the connection destination information rerequest message, and connects The destination information request message creation unit 324 is instructed to perform processing. The connection destination information request message creation unit 324 extracts the destination information (“1.0.0.0.7.6.5.2.4.2.1.8.e164num.net” attached to the connection destination information rerequest message, and extracts the extracted destination information. Is created and sent to the ENUM server 40 (step S7).

  The connection destination search unit 422 of the ENUM server 40 connects based on the destination information (“1.0.0.0.7.6.5.2.4.2.1.8.e164num.net”) attached to the connection destination information request message (ENUM Query). The destination information table 430 is searched. Here, the new connection destination information (“SIP server (C) IP address”) after the change associated with the destination information of the terminal 10 b is registered in the connection destination information table 430. The connection destination information response message creation unit 423 creates a connection destination information response message (ENUM Answer) including the connection destination information (“SIP server (C) IP address”) obtained as a result of the search by the connection destination search unit 422. The connection destination information request message (ENUM Query) is transmitted to the SIP server 20a that has transmitted the message (step S8).

The connection destination information cache table update unit 325 of the ENUM cache device 30 extracts the connection destination information “SIP server (C) IP address” attached to the received connection destination information response message (ENUM Query), and connects to the connection destination information cache. The table 330 is updated (see step S9: “connection destination information cache table 330c” in FIG. 1).
Thereby, the connection destination information cache table 330 of the ENUM cache device 30a has the same information as the latest information related to the terminal 10b, that is, the changed connection destination information stored in the connection destination information table 430 of the ENUM server 40. It becomes.

  Next, the connection destination information rerequest response message creating unit 326 of the ENUM cache device 30a creates a connection destination information rerequest response message (ENUM Answer) including the updated connection destination information “SIP server (C) IP address”. And transmitted to the SIP server 20a (step S10).

  When the message analysis unit 221 of the SIP server 20a receives the connection destination information rerequest response message (ENUM Answer), the message analysis unit 221 instructs the connection rerequest message creation unit 225 to perform processing. The connection rerequest message creating unit 225 extracts the connection destination information “SIP server (C) IP address” attached to the connection destination information rerequest response message, and includes the connection destination request (“+81425670001”). Create a message (INVITE). Then, the connection re-request message creating unit 225 sends the created connection re-request message (INVITE) to the connection destination indicated by the changed connection destination information (“SIP server (C) IP address”). SIP server 20b-2 ") (step S11).

  The accommodation terminal search unit 227 of the SIP server 20b-2 determines whether or not the terminal (here, the terminal 10b) indicated by the destination information (“+81425670001”) attached to the connection request message (INVITE) is contained. Is determined with reference to the accommodation terminal information table 230. When the accommodation terminal search unit 227 determines that the terminal 10b is accommodated because the destination information (“+81425670001”) is registered in the accommodation terminal information table 230, the SIP server 20b-2 The call connection request message creating unit 229 transmits a call connection request message (INVITE) to the terminal 10b (step S12). Then, the terminal 10b transmits a call connection response message (200 (INVITE)) indicating acceptance of the connection request to the SIP server 20b-2 (step S13).

  When the connection response message creating unit 228 of the SIP server 20b-2 receives the call connection response message (200 (INVITE)) from the terminal 10b, the connection response message creating unit 228 sends a connection response message (200 (INVITE)) indicating that the call connection is possible. It transmits to the SIP server 20a (step S14).

  Upon receiving the connection response message (200 (INVITE)), the connection request response message creating unit 226 of the SIP server 20a creates a connection request response message (200 (INVITE)) indicating that the call connection processing has been completed, and the terminal 10a (step S15).

  As described above, according to the communication system 100 and the ENUM cache update method according to the present embodiment, the destination information and the connection destination information stored in the connection destination information cache table 330 of the ENUM cache device 30 are associated with each other. Whether or not the information (ENUM cache) indicates the correct connection destination information is determined based on whether or not the call connection processing is successful, and the changed connection from the ENUM server 40 only when the call connection fails. The destination information is acquired, the ENUM cache is updated, and call connection processing is executed.

  In this way, it is possible to cope with a change in the operator network 1 of the terminal 10b without setting the valid period of the cache data in the ENUM cache device 30. Further, since it is not necessary to set the valid period of the cache data in the ENUM cache device 30, the number of accesses to the ENUM server 40 can be reduced and the load on the ENUM server 40 can be reduced. Further, when the access to the ENUM server 40 is charged, the connection to the ENUM server 40 may be performed only when connecting to the terminal 10b again after the information related to the terminal 10b is changed. It is also possible to reduce. Further, after the change of the operator network 1 of the terminal 10b, the cache data of the ENUM cache device 30 can be obtained only by making a connection request to the SIP server 10b-1 with the information before the change only once when connecting to the terminal 10b again. Can be updated. Therefore, the connection destination before the change is erroneously connected only once, and the erroneous connection can be reduced as compared with the case where the valid period of the cache data is set in the ENUM cache device 30.

  In the communication system 100 according to the present embodiment, the ENUM cache device 30 is an independent device, but the SIP server 20 may be provided with the functions of the ENUM cache device 30.

DESCRIPTION OF SYMBOLS 1 Provider network 10 Terminal 20 SIP server 21, 31, 41 Communication part 22, 32, 42 Control part 23, 33, 43 Memory | storage part 24, 34, 44 Memory part 30 ENUM cache apparatus 40 ENUM server 100 Communication system 221,321 , 421 Message analysis unit 222, 324 Connection destination information request message creation unit 223 Connection request message creation unit 224 Connection destination information re-request message creation unit 225 Connection re-request message creation unit 226 Connection request response message creation unit 227 Accommodating terminal search unit 228 Connection response message creation unit 229 Call connection request message creation unit 230 Accommodating terminal information table 322 Connection destination information cache table search unit 323, 423 Connection destination information response message creation unit 325 Connection destination information cache table update unit 3 26 Connection destination information rerequest response message creation unit 330 Connection destination information cache table 422 Connection destination search unit 430 Connection destination information table

Claims (3)

A SIP server that is installed in each carrier network and accommodates at least one terminal, and connection destination information for connection to a SIP server that accommodates the terminal is registered in association with a terminal identifier for identifying the terminal. An ENUM server having a connection destination information table, and an ENUM cache device having a cache function that is installed in each communication carrier network and has a cache function for acquiring and holding information of the connection destination information table of the ENUM server, The caller SIP server that has received the connection request message including the callee destination information that is the terminal identifier of the callee terminal from the terminal accommodated by itself connects the callee SIP server that accommodates the terminal indicated by the callee information. Inquires the ENUM cache device for destination information, connects to the SIP server on the called side, and performs mutual communication between terminals. A cormorant communication system,
The originating SIP server is
The connection destination information associated with the terminal identifier indicated by the destination information attached to the received connection request message is acquired from the ENUM cache device, and the SIP server on the receiving side indicated by the acquired connection destination information When the destination information is notified and a notification indicating that the terminal indicated by the destination information is not contained is received from the SIP server on the called side, the ENUM cache device is attached to the received connection request message. A control unit that inquires again about the connection destination information associated with the terminal identifier indicated by the destination information.
The SIP server on the called side is
A storage unit for storing an accommodation terminal information table in which a terminal identifier for identifying a terminal accommodated by itself is registered;
The terminal indicated by the destination information notified from the caller-side SIP server is searched for whether it is registered in the accommodation terminal information table. As a result of the search, the terminal indicated by the notified destination information is the accommodation. If not registered in the terminal information table, a control unit that transmits a notification that the terminal is not accommodated to the originating SIP server,
The ENUM cache device
A storage unit that stores a connection destination information cache table that registers connection destination information for connecting to a SIP server that accommodates the terminal in association with a terminal identifier for identifying the terminal;
When an inquiry is received again about the connection destination information associated with the terminal identifier indicated by the destination information from the SIP server on the calling side, the connection destination information associated with the terminal identifier indicated by the destination information is stored in the ENUM server. And a control unit that registers the acquired connection destination information in the connection destination information cache table in association with the terminal identifier;
A communication system comprising: A SIP server that is installed in each carrier network and accommodates at least one terminal, and connection destination information for connection to a SIP server that accommodates the terminal is registered in association with a terminal identifier for identifying the terminal. An ENUM server having a connection destination information table, and an ENUM cache device having a cache function that is installed in each communication carrier network and has a cache function for acquiring and holding information of the connection destination information table of the ENUM server, The caller SIP server that has received the connection request message including the callee destination information that is the terminal identifier of the callee terminal from the terminal accommodated by itself connects the callee SIP server that accommodates the terminal indicated by the callee information. Inquires the ENUM cache device for destination information, connects to the SIP server on the called side, and performs mutual communication between terminals. A cormorant communication system,
The originating SIP server is
A first connection destination information request message including the destination information attached to the received connection request message and requesting the connection destination information associated with a terminal identifier indicated by the destination information; A first connection destination information request message creation unit to be transmitted to the device;
When a first connection destination information response message including the connection destination information is received from the ENUM cache device, a connection request message including the destination information is created and a connection attached to the first connection destination information response message A connection request message creating unit that transmits to the SIP server on the called side indicated by the destination information;
When a connection response message indicating terminal non-accommodation is received from the SIP server on the called side, a connection destination information re-request message including the destination information attached to the connection request message is created and transmitted to the ENUM cache device A destination information re-request message creation unit;
When a connection destination information rerequest response message is received from the ENUM cache device, a connection rerequest message including the destination information attached to the connection request message is created and attached to the connection destination information rerequest response message A connection rerequest message creating unit that transmits to the SIP server on the receiving side indicated by the connection destination information,
The SIP server on the called side is
A storage unit for storing an accommodation terminal information table in which a terminal identifier for identifying a terminal accommodated by itself is registered;
When the connection request message or the connection re-request message is received from the calling-side SIP server, a terminal indicated by the destination information attached to the connection request message or the connection re-request message is displayed in the accommodation terminal information table. Accommodates whether or not it is registered, and if the terminal indicated by the destination information is not registered in the accommodation terminal information table as a result of the search, A terminal search part;
A connection response message creating unit that creates a connection response message indicating that the terminal is not accommodated and transmits the connection response message to the SIP server on the caller side when the determination of the accommodated terminal search unit is a terminal unaccommodated,
The ENUM cache device
A storage unit that stores a connection destination information cache table that registers connection destination information for connecting to a SIP server that accommodates the terminal in association with a terminal identifier for identifying the terminal;
The destination information attached to the first connection destination information request message received from the caller-side SIP server is extracted and associated with the terminal identifier indicated by the extracted destination information in the connection destination information cache table. A connection destination information cache table search unit for searching whether connection destination information is registered;
Second connection destination information request for creating a second connection destination information request message including the destination information attached to the connection destination information re-request message received from the SIP server on the caller side and transmitting the message to the ENUM server A message creation unit;
The connection destination information attached to the second connection destination information response message received from the ENUM server is extracted, and the extracted connection destination information is included in the destination information included in the second connection destination information request message. A connection destination information cache table update unit that associates and registers in the connection destination information cache table;
When the connection destination information cache table search unit can search the connection destination information associated with the terminal identifier indicated by the extracted destination information from the connection destination information cache table, the first information including the searched connection destination information A first connection destination information response message creating unit that creates a connection destination information response message and transmits the connection destination information response message to the SIP server on the calling side;
When the second connection destination information request message is received and the second connection destination information request message is transmitted, the second connection destination information response message is received from the ENUM server, and the second connection destination information response is received. A connection destination information re-request response message creating unit that creates the connection destination information re-request response message including the connection destination information attached to the message and transmits the message to the SIP server on the caller side, and
The ENUM server is
A storage unit for storing the connection destination information table;
The destination information attached to the second connection destination information request message received from the ENUM cache device is extracted and registered in the connection destination information table in association with the terminal identifier indicated by the extracted destination information. A connection destination search unit for acquiring connection destination information;
A second connection destination information response message creating unit that creates the second connection destination information response message including the connection destination information acquired by the connection destination search unit, and transmits the second connection destination information response message to the ENUM cache device;
A communication system comprising: A SIP server that is installed in each carrier network and accommodates at least one terminal, and connection destination information for connection to a SIP server that accommodates the terminal is registered in association with a terminal identifier for identifying the terminal. An ENUM server having a connection destination information table, and an ENUM cache device having a cache function that is installed in each communication carrier network and has a cache function for acquiring and holding information of the connection destination information table of the ENUM server, The caller SIP server that has received the connection request message including the callee destination information that is the terminal identifier of the callee terminal from the terminal accommodated by itself connects the callee SIP server that accommodates the terminal indicated by the callee information. Inquires the ENUM cache device for destination information, connects to the SIP server on the called side, and performs mutual communication between terminals. A method of cache update ENUM cache apparatus in earthenware pots communication system,
The SIP server includes a storage unit information table in which a terminal identifier for identifying a terminal accommodated by the SIP server is registered, and the ENUM cache device associates with a terminal identifier for identifying the terminal. A storage unit that stores a connection destination information cache table for registering connection destination information for connection to a SIP server that accommodates the terminal, and the ENUM server includes a storage unit that stores the connection destination information table. And
A first connection destination information request message for requesting the connection destination information associated with the terminal identifier indicated by the destination information, wherein the SIP server on the calling side includes the destination information attached to the connection request message; Creating and sending to the ENUM cache device;
The ENUM cache device extracts the destination information attached to the first connection destination information request message received from the SIP server on the caller side, and the extracted destination information is stored in the connection destination information cache table. Searching for whether or not the connection destination information is registered in association with the terminal identifier shown;
When the ENUM cache device can retrieve connection destination information associated with the terminal identifier indicated by the extracted destination information from the connection destination information cache table, first connection destination information including the retrieved connection destination information Creating a response message and sending it to the originating SIP server;
When the originating SIP server receives the first connection destination information response message including the connection destination information from the ENUM cache device, it creates a connection request message including the destination information and creates the first connection Transmitting to the SIP server on the called side indicated by the connection destination information attached to the destination information response message;
The SIP server on the receiving side searches whether or not the terminal indicated by the destination information attached to the connection request message is registered in the accommodation terminal information table, and the destination information indicates the result of the search. When the terminal is not registered in the accommodation terminal information table, determining that the terminal is not accommodated by the terminal;
A step of creating a connection response message indicating that the terminal is not accommodated, and transmitting the connection response message to the SIP server on the originating side when the SIP server on the receiving side determines that the terminal is not accommodated;
When the originating SIP server receives a connection response message indicating that the terminal is not accommodated from the terminating SIP server, it creates a connection destination information re-request message including the destination information attached to the connection request message. Sending to the ENUM cache device;
The ENUM cache device creates a second connection destination information request message including destination information attached to the connection destination information re-request message received from the caller-side SIP server, and transmits the second connection destination information request message to the ENUM server. When,
The ENUM server extracts the destination information attached to the second connection destination information request message received from the ENUM cache device, and associates the connection destination information with the terminal identifier indicated by the extracted destination information. Acquiring the connection destination information registered in the table, creating a second connection destination information response message including the acquired connection destination information, and transmitting to the ENUM cache device;
The ENUM cache device extracts connection destination information attached to the second connection destination information response message received from the ENUM server, and uses the extracted connection destination information as the second connection destination information request message. Registering in the connection destination information cache table in association with the destination information included,
A cache update method for an ENUM cache device, characterized in that:

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