JP2009253962A - Communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid occurrence of the situation, where the connection of a communication session is disabled from being controlled, without uselessly multiplexing a call control server. <P>SOLUTION: A communication system includes: a plurality of call control servers 30X, 30Y for controlling, respectively, the connection of a communication session with a communication terminal 20A, 20B, which is registered in the server respectively, as a connection destination; and a plurality of communication terminals each of which is registered in any one of the plurality of call control servers 30X, 30Y, each for performing a data communication by establishing a communication session with another device under control due to the call control server that is a registration destination. In the communication system, when a device selected as a connection destination of a communication session is a communication terminal that is not registered in a call control server, the call control server is caused to carry out processing for instructing communication terminal to register in the call control server and for controlling the connection of the communication session after the completion of the registration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a call control server that performs connection control of a communication session.

ADSL (Asymmetric Digital
With the spread of high-speed data communication technology such as Subscriber Line), it is possible to perform voice call communication (call communication using a so-called IP (Internet Protocol) telephone) and conference communication via an electric communication line such as the Internet. . For example, in this type of voice call communication, a communication session is established between communication terminals, and voice data representing the user's voice is transmitted to each communication terminal to the connection destination of the communication session. This is realized by executing a process of emitting a sound according to the transmitted audio data. As for conference communication, a communication session is established between a communication terminal used by each conference participant and a multi-point control unit (hereinafter referred to as MCU). While the same processing as that in communication is executed, the following processing is executed by the MCU. That is, the MCU receives voice data transmitted from each of a plurality of communication terminals to which a communication session is connected, and receives voice data received from other communication terminals for each of the plurality of communication terminals. To execute processing for transmitting audio data obtained by mixing.

  The establishment of a communication session between the communication terminals or a communication session between the communication terminal and the MCU is generally performed according to a protocol called SIP (Session Initiation Protocol). In SIP, a SIP number or SIP-URI corresponding to a telephone number in normal telephone communication is used as a SIP identifier for uniquely identifying a connection destination of a communication session. On the other hand, data communication via a communication network such as the Internet is used. Then, an IP address is used as an identifier for uniquely identifying each communication device. Therefore, in a communication system that provides an IP telephone service or a conference communication service, a call control server that performs mutual conversion between an SIP identifier and an IP address is generally provided. Connection control is performed.

By the way, in a mode in which connection control of a communication session is performed using a call control server, a communication failure between the call control server and another device (communication terminal or MCU) occurs when a failure occurs in the call control server. When this occurs, there is a problem that connection control of a communication session cannot be performed and voice call communication or conference communication cannot be performed at all. Therefore, it has been proposed to multiplex call control servers in order to deal with such problems (for example, Patent Document 1). This patent document 1 describes a main call control server that performs call control based on SIP (that is, connection control of a communication session) and a call in place of the main call control server when a failure occurs in the main call control server. It is disclosed that an auxiliary call control server that performs control is provided in an IP network to prepare for a failure of the main call control server. Also, in this Patent Document 1, it is proposed to configure an IP telephone apparatus that performs a call over an IP network as follows in order to promptly recognize that a failure has occurred in the main call control server. Yes. That is, the memory that stores the address information of the secondary call control server in advance and the IP address included in the received INVITE message are compared with the address information stored in the memory. It has been proposed to provide the IP telephone apparatus with a control circuit that displays an error message indicating that a failure has occurred in the server.
JP 2006-33732 A

In the technique disclosed in Patent Document 1, the secondary call control server is not used at all while the primary call control server is operating normally. There is a problem that it is not preferable in terms of cost. On the other hand, if the call control server is not multiplexed at all, if a failure occurs in the call control server or if a communication failure occurs between the communication terminal and the call control server, As described above, there is a problem that connection control cannot be performed at all.
The present invention has been made in view of the above problems, and in a communication system in which connection control of communication sessions is performed by a call control server, connection control of communication sessions can be performed while avoiding unnecessary multiplexing of call control servers. It aims at providing the technique which makes it possible to reduce the occurrence frequency of the situation which disappears.

  In order to solve the above-described problems, the present invention provides a plurality of call control servers that perform connection control of a communication session having a communication terminal registered as a connection destination as a connection destination, and register each of the plurality of call control servers with any of the plurality of call control servers. And a plurality of communication terminals that establish data communication with other devices under the control of the call control server that is the registration destination and perform data communication, and each of the plurality of call control servers includes: If the device selected as the connection destination of the communication session is a communication terminal not registered with the call control server, the communication terminal is instructed to register with the call control server, and the registration is completed. Provided is a communication system characterized in that connection control of the communication session is performed later.

  In such a communication system, even if multiplexing is performed by providing a plurality of call control servers, since each of them performs connection control of a communication session, such multiplexing is not wasted. When each of the plurality of call control servers performs communication session connection control independently, the communication terminal selected as the connection destination of the communication session is registered with the call control server requested to execute the connection control of the communication session. There is a concern that the connection control of the communication session cannot be performed. However, in the communication system, the call control server is instructed to register to the call control server, and processing for connection control of the communication session is executed in the call control server after the registration is completed. Therefore, the above problems do not occur.

  In a more preferred aspect, each of the plurality of call control servers included in the communication system is configured so that the communication terminal and another communication terminal are in response to a request from the communication terminal registered with the call control server. A device for controlling connection of a communication session, the other communication terminal selected as a connection destination of the communication session is not registered in the call control server, and the other communication terminal and the call control server If the communication terminal is not able to communicate, it instructs the requesting communication terminal to re-register with another call control server, and the communication terminal instructed to re-register performs another call control according to the instruction. It is re-registered with a server, and execution of connection control of a communication session with the other communication terminal is requested to the other call control server.

  According to such an aspect, when the other communication terminal selected as the connection destination of the communication session is not registered in the call control server requested to execute the connection control of the communication session, as described above. In addition, the call control server executes processing for instructing the other communication terminal to register. When communication with the other communication terminal is impossible due to a communication failure or the like, the call control server instructs the requesting communication terminal to re-register with another call control server. In response to the instruction, the communication terminal reregisters with another call control server in accordance with the instruction, and requests the other call control server to execute connection control of the communication session with the other communication terminal. If the other communication terminal does not register with the own device, the other call control server instructs registration with the own device, and executes communication session connection control after the registration is completed. Here, when the other call control server cannot communicate with the other communication terminal, the other call control server instructs the requesting communication terminal to re-register with another call control server. As a result, even if some kind of communication failure occurs, the frequency of occurrence of a situation in which connection control of the communication session cannot be performed at all is greatly reduced.

  In another preferred aspect, each of the plurality of call control servers included in the communication system controls connection control of a communication session between any two communication terminals among the plurality of communication terminals included in the communication system. A device that is instructed to execute connection control of a communication session between the two communication terminals among the plurality of call control servers, wherein at least one of the two communication terminals If it is not registered with the server and cannot communicate with the call control server, it instructs other call control servers to perform connection control of communication sessions between these communication terminals, and In accordance with the instruction, the control server instructs each of the two communication terminals to register the call control server, and after the registration is completed, the communication server establishes a communication set-up between the two communication terminals. And executes the ® down the connection control. According to this aspect, even when the call control server instructed to execute the connection control of the communication session cannot communicate with any of the communication terminals to which the communication session is connected, the connection is performed by another call control server. Since the substitution of the control is executed, the frequency of occurrence of a situation where connection control of the communication session cannot be performed at all is greatly reduced.

  In still another preferred aspect, each of the plurality of call control servers included in the communication system is connected to each of any two or more communication terminals of the plurality of communication terminals included in the communication system and the call control. A multipoint connection device that establishes a communication session with a server and mediates data communication between the communication terminals, and is not registered with the call control server among the two or more communication terminals; and If there is something that cannot communicate with the call control server, other call control is performed as a proxy for the process of establishing a communication session with each of the two or more communication terminals and mediating data communication. The call control server instructing the server and instructing the proxy instructs each of the two or more communication terminals to register the call control server according to the instruction, and the registration is completed. And executes the established data communication mediates communication session between each after. According to this aspect, even if the call control server instructed to establish a communication session with each of the plurality of communication terminals cannot communicate with any of the communication terminals, Since the connection control is performed, the frequency of occurrence of a situation in which connection control of the communication session cannot be performed at all is greatly reduced.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(A: System configuration)
FIG. 1 is a block diagram illustrating a configuration example of a communication system 1 according to an embodiment of the present invention.
In FIG. 1, a communication system 1 including voice communication terminals 20A and 20B connected to the communication network 10 and call control servers 30X and 30Y that are also connected to the communication network 10 is illustrated. Hereinafter, when it is not necessary to distinguish between the voice communication terminals 20A and 20B, they are simply referred to as “voice communication terminal 20”. Similarly, when it is not necessary to distinguish between the call control servers 30X and 30Y, the call control servers 30X and 30Y are indicated as “call control server 30”. Although two voice communication terminals 20 are illustrated in FIG. 1, a large number of voice communication terminals 20 are actually included in the communication system 1. Similarly, three or more call control servers 30 may be included in the communication system 1.

The communication network 10 is an electric communication line such as the Internet, for example, and mediates data communication performed according to a predetermined communication protocol. Various communication protocols may be used for each protocol layer. In this embodiment, IP is used for the network layer, and TCP (Transmission Control) is used for the transport layer.
Protocol (UDP) or UDP (User Datagram Protocol), and TELNET or RTP (Real-time Transport Protocol) is used for the application layer.

  The voice communication terminal 20 is, for example, an IP telephone device, and establishes a communication session with another device (another voice communication terminal 20 or an MCU (not shown)) according to SIP, and the connection destination of the communication session Voice data communication is performed according to RTP. In the present embodiment, each voice communication terminal 20 is assigned a unique SIP identifier (SIP number or SIP-URI described above) in advance, and each voice communication terminal 20 has a unique communication address (IP address). ) Is allocated. The voice communication terminal 20 transmits a communication message (hereinafter referred to as a registration request) in which the communication address assigned to the terminal and the SIP identifier are written to the call control server 30, and associates the communication address with the SIP identifier. Require memorizing. Hereinafter, storing the communication address and the SIP identifier in association with each other in the call control server 30 is referred to as “registering with the call control server 30”.

  In the present embodiment, which of the call control servers 30X and 30Y should be preferentially selected as the registration destination for each voice communication terminal 20 is determined in advance. For example, for the voice communication terminals 20A and 20B, the call control server 30X is preferentially selected as the registration destination, and the call control server 30Y is registered when communication with the call control server 30X is impossible due to a communication failure or the like. It is stipulated to select as the destination. This is a process in which each voice communication terminal 20 stores the communication address of each call control server and the priority order as registration destinations in association with each other, and selects registration destinations in descending order of priority. (For example, when communication with the highest priority cannot be performed due to a communication failure or the like, the next highest priority is selected as a registration destination).

  The call control server 30 is an electronic device that performs connection control of a communication session, similar to the main call control server and the secondary call control server disclosed in Patent Document 1. More specifically, when a registration request is transmitted from the voice communication terminal 20, the call control server 30 executes a process of storing the SIP identifier and communication address included in the registration request in association with each other. . When the call control server 30 receives the call connection request (for example, the INVITE message in which the SIP identifier of the call destination is written) transmitted from the communication terminal, the call control server 30 receives the destination of the call connection request from the stored contents of the own device. The communication address of the communication terminal to be specified is specified, and a process of transferring the call connection request to the specified destination is executed. Thereby, connection control of the communication session between the communication terminal that is the transmission source of the call connection request and the communication terminal that is the transfer destination is realized.

  Thus, the communication system 1 is the same as the technique disclosed in Patent Document 1 described above in that it has two call control servers 30 (that is, call control servers 30X and 30Y). However, this embodiment is different from the technique disclosed in Patent Document 1 in that each of the two call control servers 30 is always operated so as to perform connection control of a communication session. As a result, providing a plurality of call control servers in the communication system 1 prevents unnecessary multiplexing.

  However, on the other hand, the device that is the destination of the call connection request is not registered with the call control server that received the call connection request (for example, when it is not registered with any call control server or the other call control server). Such as when registering with a server). For example, in a situation where the voice communication terminal 20A registers with the call control server 30X and the voice communication terminal 20B registers with the call control server 30Y, a call connection request with the voice communication terminal 20B as the call destination is sent to the voice communication terminal. Such a situation occurs when 20A transmits to the call control server 30X. As described above, when the voice communication terminal 20 as the transfer destination of the call connection request is not registered in the call control server that has received the call connection request, the conventional call control server performs communication according to the call connection request. Session connection control could not be performed.

  On the other hand, in this embodiment, the occurrence of the above-described problem is avoided by causing each of the voice communication terminals 20 and each of the call control servers 30 to perform processing characteristic of this embodiment. Further, in the present embodiment, even when communication with one of the two call control servers 30 becomes impossible due to a communication failure or the like, the other call control server 30 performs processing characteristic of the present embodiment. As a result, the occurrence of a situation where connection control of the communication session is not performed at all is avoided. Hereinafter, the call control server 30 that significantly shows the features of the present embodiment will be mainly described.

(B: Configuration of the call control server 30)
FIG. 2 is a block diagram illustrating a configuration example of the call control server 30.
As shown in FIG. 2, the call control server 30 mediates data exchange between the control unit 310, the communication interface (hereinafter referred to as “I / F”) unit 320, the storage unit 330, and each of these components. A bus 340 is provided.

  The controller 310 is, for example, a CPU (Central Processing Unit). The control unit 310 operates according to the control program 332 b stored in the storage unit 330 and functions as a control center of the call control server 30. The processing executed by the control unit 310 according to the control program 332b will be clarified later.

The communication I / F unit 320 is, for example, a NIC (Network
Interface Card) and is connected to the communication network 10. The communication I / F unit 320 receives data transmitted via the communication network 10 (in this embodiment, various communication messages conforming to SIP, control commands transmitted according to TELNET, and the like), and receives the data. The data delivered from the control unit 310 is sent to the communication network 10 while being delivered to the control unit 310.

  The storage unit 330 includes a volatile storage unit 331 and a nonvolatile storage unit 332. The volatile storage unit 331 is, for example, a RAM (Random Access Memory), and is used by the control unit 310 as a work area when executing the control program 332b. On the other hand, the non-volatile storage unit 332 is a non-volatile memory such as a hard disk or a flash ROM (Flash Read Only Memory). The nonvolatile storage unit 332 stores a backup machine identifier 332a in addition to the control program 332b described above.

  The backup machine identifier 332a is an identifier that uniquely indicates a call control server 30 (hereinafter referred to as a backup machine) that performs connection control on behalf of the call control server 30 when communication session connection control cannot be performed due to a communication failure or the like. . In the present embodiment, the communication address of the backup machine is used as the backup machine identifier 332a. For example, the communication address of the call control server 30Y is stored in advance as the backup machine identifier 332a in the nonvolatile storage unit 332 of the call control server 30X, and the backup machine identifier is stored in the nonvolatile storage unit 332 of the call control server 30Y. The communication address of the call control server 30X is stored in advance as 332a. As described above, in the aspect in which the communication address of the other call control server 30 is stored as a backup device identifier in each of the two call control servers 30 included in the communication system 1, The control unit 310 compares the communication address of the connection control proxy request source with the backup identifier 332a, and if they match, executes a process of returning an error notification without performing connection control proxy. Of course, it is also good. This is to prevent the proxy request for connection control between these two units from being repeated indefinitely when both of the call control servers 30X and 30Y cannot perform connection control of the communication session due to communication failure. When the communication system 1 includes three or more call control servers 30, it is of course possible to store a plurality of backup device identifiers 332a. For example, when the communication system 1 includes N (N is an integer of 3 or more) call control servers 30, the non-volatile storage unit 332 of each call control server 30 has another N−1 units. The communication address of the call control server 30 can be stored as a backup machine identifier. Further, in the aspect in which a plurality of backup machine identifiers are written in the non-volatile storage unit 332 in this way, the priority order when the backup machine identifier is selected as a backup machine is associated with each other, and the priority order You may make it select a backup machine in order with high.

  As shown in FIG. 2, the control program 332b is a program that causes the control unit 310 to execute three processes, a registrar process, a proxy process, and a communication control process. Here, in the registrar process, when a registration request transmitted from the voice communication terminal 20 is received, the SIP identifier included in the registration request and the communication address are associated with each other in the volatile storage unit 331. This is a process of writing to a registry table (not shown in FIG. 2). The proxy processing refers to the stored contents of the registry table when the call connection request transmitted from the voice communication terminal 20 is received, specifies the device as the call destination, and sends the call connection request to the device. Is a process of transferring.

The communication control process in FIG. 2 registers the call connection request to the call control server 30 when the device to which the call connection request is transferred is the voice communication terminal 20 that has not registered with the own device. This is a process for transmitting a control command (hereinafter referred to as a registration request) in accordance with TELNET. Further, in this communication control process, when a registration request cannot be transmitted or a call connection request cannot be transferred due to a communication failure, a control command (hereinafter referred to as proxy) is instructed to the call control server 30 indicated by the backup machine identifier 332a. A request is transmitted according to TELNET.
The above is the configuration of the call control server 30.

(C: Operation)
Next, taking as an example a case where communication between the voice communication terminal 20A and the call control server 30X is disabled due to a communication failure, operations performed by the voice communication terminal 20 and the call control server 30 will be described with reference to the drawings. In FIG. 3, various communication messages transmitted and received in accordance with SIP are indicated by solid arrows, and various control commands transmitted and received in accordance with TELNET are indicated by dotted arrows (the same applies to FIGS. 4 to 6).

(C-1: Operation when calling from voice communication terminal 20A to voice communication terminal 20B)
First, referring to FIG. 3, the operation when the voice communication terminals 20A and 20B make a call from the voice communication terminal 20A to the voice communication terminal 20B in a situation where neither of the call control servers 30X and 30Y registers. I will explain.
As described above, in order to use connection control of the communication session by the call control server 30, it is necessary to register with the call control server 30. As described above, in the present embodiment, the voice communication terminal 20A is predetermined to register with the call control server 30X with priority. For this reason, when the control unit (not shown) of the voice communication terminal 20A is instructed by the user to execute a call to the voice communication terminal 20B, it first tries to register with the call control server 30X. Specifically, the control unit of the voice communication terminal 20A transmits a registration request with the communication address of the call control server 30X as a destination address.

  In this operation example, communication between the voice communication terminal 20A and the call control server 30X is disabled due to a communication failure, and therefore the registration request does not reach the call control server 30X (see FIG. 3). A timeout occurs (a response is not returned even if a predetermined timeout period elapses after the registration request is transmitted). Due to the occurrence of this transmission timeout, the control unit of the voice communication terminal 20A detects that communication with the call control server 30X is impossible, and retransmits a registration request to the call control server 30Y (see FIG. 3). . In the present embodiment, it is detected that communication with the call control server 30X that is the destination of the registration request is impossible due to the occurrence of a transmission timeout for the registration request. However, prior to sending the registration request, it is detected whether communication with the destination of the registration request is possible using an existing tool (for example, PING) for confirming communication with the communication partner. May be.

  When receiving the registration request via the communication I / F unit 320, the control unit 310 of the call control server 30Y performs the above-described registrar processing and performs registration of the voice communication terminal 20A. When the registrar processing is completed, the control unit 310 of the call control server 30Y sends a registration request notification source (that is, the voice communication terminal 20A) to notify the registration completion (hereinafter referred to as registration completion notification). (See FIG. 3). When the control unit of the voice communication terminal 20A receives the registration completion notification returned from the call control server 30Y and detects the registration completion, the control unit (in this operation example, the voice communication terminal) 20B) is transmitted to the call control server 30Y (see FIG. 3), and the call control server 30Y is requested to execute communication session connection control.

  Upon receiving the call connection request via the communication I / F unit 320, the control unit 310 of the call control server 30Y receives a device (that is, a communication session connection destination) designated by the call connection request ( That is, it is determined by referring to the stored contents of the registry table whether or not the voice communication terminal 20B) registers with the call control server 30Y. When it is determined that the device designated as the connection destination of the communication session is registered in the call control server 30Y, the control unit 310 reads the communication address of the call destination from the registry table, and performs the communication. The call connection request is transferred with the address as the destination. On the contrary, if it is determined that the registration has not been performed, a registration request is transmitted to the device designated as the connection destination of the communication session. Here, when the device that is the transfer destination of the call connection request is not registered in the own device, the communication address that is the transmission destination of the registration request cannot be specified from the stored contents of the registration table, but the control program 332b. Each time the execution of the process is completed, the stored contents of the registry table at that time are stored in the nonvolatile storage unit 332, the history is retained, and the communication address that is the transmission destination of the registration request is specified by referring to the past history. You can do it. In this operation example, the voice communication terminal 20B is selected as the connection destination of the communication session, and the voice communication terminal 20B is not registered in the call control server 30Y. Therefore, the control unit 310 requests the voice communication terminal 20B to register. Is transmitted (see FIG. 3).

  When receiving the registration request transmitted from the call control server 30Y, the control unit (not shown) of the voice communication terminal 20B executes a process of transmitting the registration request according to the control command written in the registration request ( (See FIG. 3). Thereby, registration for the voice communication terminal 20B is performed by the call control server 30Y. When registration for voice communication terminal 20B is completed in this way, control unit 310 transfers the call connection request received from voice communication terminal 20A to voice communication terminal 20B (see FIG. 3).

  When the control unit of the voice communication terminal 20B receives the call connection request, the control unit notifies the user by emitting a ringing tone, and performs an operation of permitting the incoming call, for example, pressing an off-hook button. Then, a communication message for permitting establishment of the communication session (hereinafter referred to as connection permission notification) is returned (see FIG. 3). The connection permission notification returned from the voice communication terminal 20B is transferred to the voice communication terminal 20A by the call control server 30Y (see FIG. 3). When the voice communication terminal 20A receives the connection permission notification transferred in this way, a communication session is established between the voice communication terminal 20A and the voice communication terminal 20B, and voice data communication according to RTP is performed by the voice communication terminal. It starts between 20A and 20B.

  As described above, according to the present embodiment, communication between the voice communication terminal 20A and the voice communication terminal 20B can be performed even when the voice communication terminal 20A and the call control server 30X cannot communicate with each other due to a communication failure. There is no problem in session connection control, and there is no problem in voice data communication between both terminals. In addition to the communication failure, a failure of the call control server 30X can be considered as a cause of the communication failure between the voice communication terminal 20A and the call control server 30X. Thus, even when the voice communication terminal 20A cannot communicate with the call control server 30X due to a failure of the call control server 30X, a transmission timeout occurs for a registration request transmitted from the voice communication terminal 20A to the call control server 30X. Therefore, each of the voice communication terminals 20A and 20B and the call control server 30Y executes the same operation as the above-described operation, and the voice data communication between the voice communication terminal 20A and the voice communication terminal 20B is hindered. There is nothing.

(C-2: Operation when calling from voice communication terminal 20B to voice communication terminal 20A)
Next, the voice communication terminal 20A does not register with either of the call control servers 30X and 30Y, while the voice communication terminal 20B does not register with the call control server 30X, and the voice communication terminal 20B to the voice communication terminal 20A. The operation when a call is made to will be described with reference to FIG.
In this operation example, since the voice communication terminal 20B is registered in the call control server 30X, the control unit (not shown) of the voice communication terminal 20B causes the user to execute a call to the voice communication terminal 20A. When instructed, a call connection request to the call destination designated by the user (that is, the voice communication terminal 20A) is transmitted to the call control server 30X (see FIG. 4), and a communication session is transmitted to the call control server 30X. Request execution of connection control.

  When the control unit 310 of the call control server 30X receives the call connection request via the communication I / F unit 320, the device (that is, the connection destination of the communication session) selected as the call destination in the call connection request ( That is, it is determined by referring to the stored contents of the registry table whether or not the voice communication terminal 20A) is registered in the call control server 30X, and processing corresponding to the determination result is executed. In this operation example, since the voice communication terminal 20A does not register with the call control server 30X, the control unit 310 transmits a registration request to the voice communication terminal 20A. However, since communication between the voice communication terminal 20A and the call control server 30X is impossible due to a communication failure, the registration request does not reach the voice communication terminal 20A and a transmission timeout occurs. When a transmission timeout occurs in this way, the control unit 310 detects that communication with the voice communication terminal 20A is impossible, and the voice communication terminal 20B that is the transmission source of the call connection request is detected. Error notification (see FIG. 4). This error notification is for instructing the transmission source of the call connection request to re-register with another call control server 30 and to receive communication session connection control by the other call control server 30. .

  When receiving the error notification, the control unit of the voice communication terminal 20B transmits a registration request to the call control server 30Y (see FIG. 4) and changes the registration destination to the call control server 30Y. The operation executed by the control unit 310 of the call control server 30Y when receiving this registration request is the same as the operation when receiving the registration request transmitted from the voice communication terminal 20A in the operation example (C-1) described above. Are the same. Then, the control unit of the voice communication terminal 20B receives the registration completion notification returned from the call control server 30Y, and when detecting the registration completion, the control unit requests the voice communication terminal 20A to connect a communication session. A call connection request is transmitted to the call control server 30Y (see FIG. 4).

  When the control unit 310 of the call control server 30Y that has received the call connection request transmitted from the voice communication terminal 20B receives the call connection request transmitted from the voice communication terminal 20A in the operation example (C-1) described above. Similarly, the registration request is transmitted to the voice communication terminal 20A designated as the connection destination of the communication session, and when the registration is completed, the call connection request received from the voice communication terminal 20B is transferred to the voice communication terminal 20A. Thereafter, a communication session is established between the voice communication terminals 20B and 20A in the same manner as in the operation example (C-1) described above, and voice data communication in accordance with RTP is started.

(C-3: Operation when conferencing a meeting for the voice communication terminals 20A and 20B)
Next, in a situation where the voice communication terminals 20A and 20B are not registered in any of the call control servers 30X and 30Y, an instruction to execute a conference call for the voice communication terminals 20A and 20B is sent to the call control server 30. The operation when given by the operation manager will be described with reference to FIG. Here, the convocation call is to prompt each voice communication terminal 20 to perform registration for holding a remote conference by the user of the voice communication terminal 20, and after completing registration for each voice communication terminal 20, the voice communication terminals This is a process for establishing a communication session between the two.

  When the control unit 310 of the call control server 30X is given an instruction to execute a conference call via an operation unit (not shown), the two voice communication terminals selected by the operation manager or the like as the target of the conference call It is determined whether 20 is registered in its own device, and processing according to the determination result is executed. Here, the operation manager or the like can arbitrarily select two of the plurality of voice communication terminals 20 included in the communication system 1 that are the targets of the conference call. In this operation example, the target of the conference call is selected. Voice communication terminal 20A and voice communication terminal 20B are selected. As described above, since neither the voice communication terminals 20A and 20B register with the call control server 30X, the control unit 310 transmits a registration request to the voice communication terminals 20A and 20B, and prompts execution of registration. . However, in this operation example, communication between the voice communication terminal 20A and the call control server 30X becomes impossible due to a communication failure, so that a transmission timeout occurs for a registration request transmitted to the voice communication terminal 20A. As shown in FIG. 5, when the control unit 310 detects that communication with the own device is impossible for any of the two voice communication terminals 20 selected as the target of the meeting, A proxy request is sent to the call control server 30 indicated by the backup machine identifier 332a (that is, the call control server 30Y) to instruct the conference call proxy.

  When the control unit 310 of the call control server 30Y receives the proxy request via the communication I / F unit 320, the control unit 310 executes a meeting invitation according to the proxy request. More specifically, as shown in FIG. 5, the control unit 310 registers each of the two voice communication terminals 20 selected as a meeting invitation target (in this operation example, the voice communication terminals 20A and 20B). When a request is transmitted and a registration request returned from each voice communication terminal 20 in response to the registration request is received, registration is executed in accordance with the registration request. After that, when registration for each of the two voice communication terminals 20 selected as the target of the meeting is completed, the control unit 310 completes either one of the voice communication terminals 20 (in this operation example, voice communication). A control command (hereinafter referred to as a call connection request) is sent to the terminal 20A) to instruct the other (ie, the voice communication terminal 20B) to send a call connection request to request connection of a communication session. . Here, various modes are conceivable for selecting a transmission destination of the call connection request from the two voice communication terminals 20 selected as the conference target. Specifically, this is a mode in which a call connection request is transmitted to a younger communication address of the two voice communication terminals and vice versa.

  As shown in FIG. 5, when receiving the call connection request, the control unit of the voice communication terminal 20A returns a call connection request according to the call connection request. When receiving the call connection request returned in this way, the control unit 310 of the call control server 30Y, as shown in FIG. 5, sends the call connection request to the voice communication terminal 20B that is the call destination of the call connection request. And a control command (hereinafter referred to as a connection permission request) for instructing execution of processing in response to the call connection request is transmitted to the voice communication terminal 20B. Here, the connection permission request is transmitted to the voice communication terminal 20B, which is the call destination by the call connection request, without causing the user of the voice communication terminal 20B to perform an operation such as pressing an off-hook button. This is because a communication session is established between the voice communication terminal 20A and the voice communication terminal 20B.

  When receiving the call connection request and the connection permission request, the control unit of the voice communication terminal 20B executes a process for permitting the call connection in accordance with the control command written in the connection permission request, and controls the connection permission notification. A reply is sent to the server 30Y (see FIG. 5). Thereafter, as shown in FIG. 5, a communication session is established between the voice communication terminals 20B and 20A as in the above-described operation example (C-1), and voice data communication according to RTP is started.

  As described above, according to the present embodiment, the communication system 1 includes the plurality of call control servers 30, but each of them is always operated as a call control server, so that unnecessary multiplexing is performed. Never become. Further, since each of the plurality of call control servers 30 is always operated as a call control server, it is possible to perform load distribution using a load balancer such as a load balancer. Furthermore, according to the present embodiment, communication between the call control server 30 defined as the registration destination and the call control server 30 instructed to control connection of the communication session and the voice communication terminal 20 is impossible due to a communication failure or the like. Even if it is, the connection control is performed by another call control server 30. For this reason, the frequency of occurrence of a situation in which connection control of the communication session between the voice communication terminals 20 cannot be performed at all is greatly reduced.

(D: deformation)
As mentioned above, although one Embodiment of this invention was described, of course, you may add the deformation | transformation described below to this Embodiment.
(1) In the embodiment described above, when instructed to execute a conference call for the voice communication terminals 20A and 20B, both terminals are prompted to perform registration, and a communication session is established between both terminals after registration is completed. The call control server 30 is caused to execute the processing to be performed. However, in the case where the call control server 30 is an MCU that mediates voice data communication between a plurality of arbitrarily selected voice communication terminals 20, each of the plurality of voice communication terminals 20 selected as a target of a meeting call. Must establish a communication session between the device and the device. In this case, the process shown in FIG. 6 may be executed by the control unit 310 of the call control server 30. As is clear from comparison between FIG. 6 and FIG. 5, the difference between the operation according to this modification and the operation described in the operation example (C-3) described above is selected as the target of the meeting call. After the registration for the voice communication terminal 20 is completed, the control unit 310 of the call control server 30Y transmits a call connection request and a connection permission request to each of the voice communication terminals 20. is there.

  In the present modification, when the control unit of each voice communication terminal 20 selected as the target of the meeting receives the call connection request and the connection permission request, the control unit returns a connection permission notification according to the connection permission request. Execute. As a result, a communication session is established between each of the plurality of voice communication terminals 20 selected as the target of the conference and the call control server 30Y, and between each of the plurality of voice communication terminals 20 and the call control server 30Y. Thus, audio data is transmitted and received. As described above, since the call control server 30 is an MCU in this modification, the call control server 30Y receives from each other voice communication terminal 20 to each voice communication terminal 20 to which the communication session is connected. The voice data obtained by mixing the voice data is returned. In each of the plurality of voice communication terminals 20 selected as the target of the conference call, sound is emitted according to the voice data returned from the call control server 30Y. Therefore, each selected as the target of the conference call The user of the voice communication terminal 20 can listen to the voices of the users of all the other voice communication terminals 20, and thus the remote conference is performed.

(2) In the above-described embodiment, the present invention is applied to the call control server 30 that performs connection control of a communication session for voice data communication. However, the application target of the present invention is not limited to such a call control server, and the present invention is applied to a call control server that controls connection of a communication session for transmitting / receiving other types of data such as image data. Of course, it may be applied. The protocol that defines the connection procedure of the communication session is not limited to SIP. Other protocols such as H.323 may be used.

(3) In the above-described embodiment, the non-volatile storage unit 332 stores in advance the control program 332b that causes the control unit 310 to execute an operation that significantly shows the characteristics of the call control server according to the present invention. However, the control program 332b may be distributed by being written on a computer-readable recording medium such as a CD-ROM (Compact Disk-Read Only Memory) or downloaded via an electric communication line such as the Internet. May be distributed. The control program 332b distributed in this way is stored in a storage unit (hard disk or the like) of a general computer device such as a personal computer, and the control unit (CPU) of the computer device is operated according to the control program 332b. Thus, it is possible to cause the computer apparatus to execute the same processing as that of the call control server of the above embodiment.

It is a figure which shows the structural example of the communication system 1 which concerns on one Embodiment of this invention. 2 is a diagram illustrating a configuration example of a call control server 30 included in the communication system 1. FIG. 3 is a diagram showing an example of a communication sequence in the communication system 1. FIG. 3 is a diagram showing an example of a communication sequence in the communication system 1. FIG. 3 is a diagram showing an example of a communication sequence in the communication system 1. FIG. It is a figure which shows an example of the communication sequence in the communication system of a modification (1).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Communication system, 10 ... Communication network, 20, 20A, 20B ... Voice communication terminal, 30, 30X, 30Y ... Call control server, 310 ... Control part, 320 ... Communication I / F part, 330 ... Memory | storage part, 331 ... Volatile storage unit, 332... Nonvolatile storage unit, 332 a... Backup machine identifier, 332 b.

Claims (4)

A plurality of call control servers for controlling connection of a communication session with a communication terminal registered as each connection destination;
A plurality of communication terminals each registering with any of the plurality of call control servers, establishing a communication session with other devices under the control of the call control server which is the registration destination, and performing data communication;
With
Each of the plurality of call control servers includes:
If the device selected as the connection destination of the communication session is a communication terminal not registered with the call control server, the communication terminal is instructed to register with the call control server, and the registration is completed. A communication system, wherein connection control of the communication session is performed later. Each of the plurality of call control servers includes:
A device that performs connection control of a communication session between the communication terminal and another communication terminal in response to a request from the communication terminal registered in the call control server,
When the other communication terminal selected as the connection destination of the communication session does not register with the call control server and the other communication terminal and the call control server cannot communicate, the request source Instruct the communication terminal to re-register with another call control server,
The communication terminal instructed to re-register re-registers with another call control server according to the instruction, and requests the other call control server to execute connection control of the communication session with the other communication terminal. The communication system according to claim 1. Each of the plurality of call control servers includes:
An apparatus for controlling connection of a communication session between any two communication terminals of the plurality of communication terminals;
Those instructed to execute connection control of a communication session between the two communication terminals among the plurality of call control servers,
If at least one of the two communication terminals does not register with the call control server and cannot communicate with the call control server, proxy connection control for the communication session between the communication terminals is performed. Instruct the call control server,
The call control server instructed to perform the proxy instructs each of the two communication terminals to register to the call control server according to the instruction, and after the registration is completed, connection of the communication session between the two communication terminals The communication system according to claim 1, wherein control is executed. Each of the plurality of call control servers includes:
A multipoint connection device that establishes a communication session between each of the two or more communication terminals of the plurality of communication terminals and the call control server, and mediates data communication between the communication terminals;
If the two or more communication terminals do not register with the call control server and cannot communicate with the call control server, each of the two or more communication terminals Instruct the other call control server to perform the process of mediating data communication by establishing a communication session between
In response to the instruction, the call control server instructed to perform registration of the call control server to each of the two or more communication terminals, and after the registration is completed, a communication session with each of the call control servers The communication system according to claim 1, wherein mediation of data communication is executed.

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