KR100847513B1 - Centrex service system and driving method of application server - Google Patents

Abstract

A centrex service system and a method for driving an application server are provided to offer a centrex service to preset centrex groups by being interlocked with PSTN, BcN, 3G-IMS, and a 2G mobile network, thereby being compatible between different networks and providing an integrated centrex service regardless of a type of network. A centrex service system comprises an application server(100), a first network(N1), a second network(N2), a third network(N3), a fourth network(N4), and a media server(200). The N1 is a PSTN(Public Switched Telephone Network) and includes an SSP(Service Switching Point)(310) and an STP(Signaling Transfer Point)(320). The N2 is a BcN(Broadband Convergence Network) and includes an access gateway(410) and an SSW(Soft Switch)(420). The N3 is a third-generation internet protocol multimedia subsystem network and includes an RNS(Radio Network Subsystem)(510), a GPRS(General Packet Radio Service) SGSN(Serving GPRS Support Node)/GGSN(Gateway GPRS Support Node)(520), and a CSCF(Call Session Control Function)(530). The N4 is a second-generation mobile network and includes a BSS(Base Station Subsystem)(610) and an MSC(Mobile Switching Center)(620). The application server stores preset centrex group information and provides a centrex service to a preset centrex group(G1~G5) by being interlocked with the STP, the SSW, the CSCF, and the MSC included into each of the networks of N1 to N4. A media server(200) supports special functions such as the video conference and announcement transmission of the application server.

Description

CENTREX SERVICE SYSTEM AND DRIVING METHOD OF APPLICATION SERVER}

1 is a block diagram illustrating a Centrix service system according to an embodiment of the present invention.

2 is a block diagram schematically illustrating an internal configuration of an application server 100 according to an exemplary embodiment of the present invention.

3 is a block diagram schematically illustrating a CMS 110 according to an embodiment of the present invention.

4 is a block diagram schematically illustrating a DBS 120 according to an embodiment of the present invention.

5 is a block diagram schematically illustrating an SES 130 according to an embodiment of the present invention.

FIG. 6 is a flowchart illustrating a process of performing a function of receiving a terminal between terminals accommodated in different heterogeneous networks through a Centrix service system according to an exemplary embodiment of the present invention.

The present invention relates to a method of running a Centrix service system and an application server.

The Centrix service is a service mainly intended for an enterprise, and refers to a customized service provided for a corporate environment by grouping specific terminals among a plurality of terminals accommodated in an exchange.

The Centrix service system is for providing a Centrix service.

The general Centrix service system is classified into a Public Switched Telephone Network (PSTN) Centrix service system and a Mobile Network Centrix service system according to the type of communication network providing the service.

In recent years, due to the development of communication technology, the need for a service compatible with different heterogeneous communication networks is increasing without limitations depending on the type of communication network.

However, a general Centrix service system cannot provide a compatible Centrix service between different heterogeneous communication networks, and therefore, there is an urgent need to construct a Centrix service system compatible between different heterogeneous communication networks without restriction of the type of communication network. Situation.

In order to solve such a problem, the present invention provides a method of driving a Centrix service system and an application server.

The Centrix service system according to an aspect of the present invention is a Centrix service system that provides a customized Centrix service to a terminal included in a Centrix group, and includes a first communication network of two or more heterogeneous networks operated based on different protocols. A call control server and a centric service logic for providing a centric service by connecting a call between the first terminal and a second terminal included in a second communication network in response to a request for providing a centric service received from a first terminal included in And a service execution server configured to generate and transmit the centrix service corresponding to the centrix service provision request to the call control server according to the centrix service logic.

In addition, a method of driving an application server according to an aspect of the present invention is a method of driving an application server that provides a customized centric services to a plurality of terminals, a) a first call connection request from a first terminal to a preset first; Calling a second terminal having a first code, b) receiving call state notification information corresponding to the call from the second terminal, c) connecting a second call including the first code from a third terminal Receiving a request, d) making a call cancellation request to the second terminal, e) receiving a response according to the call cancellation request from the second terminal, and responding to the second call connection request to the third terminal; Transmitting a corresponding response and f) connecting a call between the first terminal and the third terminal.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise.

Now, a method of driving a Centrix service system and an application server according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a Centrix service system according to an embodiment of the present invention.

As shown in FIG. 1, the Centrix service system according to an exemplary embodiment of the present invention includes an application server 100, a first communication network N1, a second communication network N2, a third communication network N3, A fourth communication network N4 and a media server 200 are included.

The first communication network N1 is a PSTN and includes a Service Switching Point (SSP) 310 and a Signaling Transfer Point (STP) 320. The SSP 310 performs access control and management of a plurality of terminals, and the STP 320 manages a plurality of SSPs 310.

The second communication network N2 is a broadband convergence network (BcN) that provides communication, broadcasting, and Internet services to terminals by integrating a communication network into a broadband network, and includes an access gateway 410 and A soft switch (hereinafter referred to as SSW) 420 is included.

The access gateway 410 is a media gateway device that uses an open network structure to build a single network that accommodates packet-based multi services. The access gateway 410 accommodates a Private Branch Exchange (PBX), which is an access node, and accesses a terminal linked to a time division multiplexing (TDM) voice network through an E1 interface. Perform control and management. In addition, the access gateway 410 accommodates an integrated subscriber access device, such as a Fiber Loop Carrier (FLC), and has a primary group speed interface (ISDN), which is a type of Integrated Services Digital Network (ISDN) service. Primary Rate Interface (PRI) processing

The SSW 420 manages the access gateway 410 and performs various call processing and additional service functions based on the Session Initiation Protocol (SIP) to provide voice services and various multimedia services.

The third communication network N3 is a third generation IP-based multimedia service (3G-IP Multimedia Subsystem) network that provides data, voice, and wireless network services. The third communication network N3 is a base station controller (RNS) 510, GPRS. (General Packet Radio Service) support node (SGSN / GGSN, 520) and Call Session Control Function (hereinafter referred to as CSCF) 530.

The RNS 510 performs access control and management of a plurality of wireless terminals accommodated in a base station (not shown). The GPRS support node 520 is an intermediary between the CSCF 530 and the RNS 510 through services such as service identification, routing, address translation, encryption, and tunneling. Play a role.

CSCF 530 manages multiple RNSs 510 through multiple GPRS support nodes 520.

The fourth communication network N4 is a second generation mobile network, and includes a base station subsystem (BSS) 610 and a mobile switching center (MSC) 620. . The MSC 620 performs access control and management for multiple wireless terminals, and the BSS 610 manages multiple MSCs 620.

The STP 320, SSW 420, CSCF 530, and MSC 620 included in each of the first to fourth communication networks N1 to N4 request the provision of the call center service from the receiving terminal. If it is a specific number, the originating call is transmitted to the application server 100.

In this case, the specific number is a number previously set for the Centrix service, and may be a two-digit or three-digit number including the information of the receiving terminal, such as an extension number for call connection inside the enterprise. Alternatively, it may consist of a combination of a predetermined number or symbol designated for the Centrix service and a number including information of the receiving terminal.

The application server 100 stores preset centric group information for providing a centric service, and based on this, the STP 320 and the SSW 420 included in each of the first to fourth communication networks N1 to N4. , In conjunction with the CSCF 530 and the MSC 620, provides a Centrix service. Here, the Centrix service refers to an enterprise-specific service that provides multimedia services such as video conferencing to a terminal included in the Centrix group through a conventional Private Branch Exchange (PBX). do. That is, the application server 100 is an extension call function, call truncation call, call forwarding call, designated time notification, call reservation, call waiting call, outgoing call restriction, incoming call transfer, outgoing call to the terminal included in the Centrix group It provides not only basic call management functions such as incoming call restriction and incoming call restriction by time zone, but also special functions such as three-way call message processing, announcement broadcasting and video conferencing. Here, the Centrix group may be terminals accommodated in one of the first to fourth communication networks N1 to N4, as shown by G1, G2, G4, and G5 of FIG. 1. The terminal may be accommodated in two or more communication networks among the first to fourth communication networks N1 to N4, such as G3.

When the application server 100 receives a specific number requesting to provide a centric service from a terminal in an area controlled by the STP 320, the SSW 420, the CSCF 530, and the MSC 620, the application server 100 may provide a service. It is determined whether the requested originating terminal and the receiving terminal to which the calling terminal attempts to access the call are included in the preset centric group. If there is a terminal that is not included in the Centrix group among the originating terminal and the receiving terminal, the application server 100 provides a Centrix service for the terminal included in the Centrix group, and for a terminal not included in the Centrix group. Only general call service is provided. On the contrary, if both the calling terminal and the receiving terminal are included in the centric group, the application server 100 provides the centric service to the calling terminal and the receiving terminal. In this case, the transmitting terminal and the receiving terminal may be included in the same centric group or may be included in different centric groups.

The media server 200 supports special functions such as video conferencing or guide broadcast transmission of the application server 100. The media server 200 stores preset guide announcements and specific media environment information preset to be provided during video conferencing. When the application server 100 receives a request for providing a service such as a video conference or announcement broadcast from a terminal included in a Centrix group, the application server 100 transmits specific media environment information or announcement announcement stored in the media server 200 to the originating terminal and the receiving terminal. All or to a specific receiving terminal designated by the calling terminal.

Hereinafter, the application server 100 according to the exemplary embodiment of the present invention illustrated in FIG. 1 will be described in detail with reference to FIGS. 2 to 7.

2 is a block diagram schematically illustrating an internal configuration of an application server 100 according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the application server 100 according to an embodiment of the present invention includes a call management server (CMS) 110 and a database server DBS 120. ), Service Execution Server (hereinafter referred to as SES) 130, Operation & Management Server (hereinafter referred to as OMS) 140 and Element Management Server (hereinafter referred to as EMS) 150 ). Since the functions and roles of the OMS 140 and the EMS 150 are well known to those skilled in the art, the description thereof will be omitted and the CMS 110, DBM, and SES 130 which are directly related to the Centrix service processing will be omitted. Only explain.

When the CMS 110 receives the Centrix service request from the STP 320, the SSW 420, the CSCF 530, and the MSC 620, the CMS 110 transmits the request to the SES 130 to the processing result of the SES 130. It provides a service according to the terminal.

The DBS 120 stores various data for providing the Centrix service and manages the data.

The SES 130 executes service logic corresponding to the service request information received from the CMS 110 and transmits the result to the CMS 110.

On the other hand, as shown in Figure 2, the application server 100 according to an embodiment of the present invention includes a data transmission bus for internal data delivery, through which the CMS (110), DBM, SES (130), OMS ( 140 and the EMS 150 are implemented to input and output data to and from each other.

In addition, although not shown in Figure 2, the application server 100 according to an embodiment of the present invention is a system management for the operation management of the Centrix service, that is, statistics, billing, subscriber management, set up the Centrix group and the system of the operator It can be set to work with a web server. At this time, the system management web server is connected to a billing center for billing, a customer center for resolving inconveniences in using the service, and a separate operation management center for operation management of the Centrix service system. Is implemented.

3 is a block diagram schematically illustrating a CMS 110 according to an embodiment of the present invention.

As shown in FIG. 3, the CMS 110 in accordance with an embodiment of the present invention includes a network adapter 112 and a channel management / call distribution processor 114.

The network adapter 112 includes an STP 320 included in each of the first to fourth communication networks N1 to N4 through a SIP, an intelligent network application protocol (INAP), and a wireless intelligent network (WIN) protocol. ), Data transmission and reception with the SSW 420, the CSCF 530, and the MSC 620 are performed.

The channel management / call distribution processor 114 transmits the Centrix service request information received through the network adapter 112 to one SES 130 of the plurality of SES 130-1 to 130 -N, and the SES ( According to the service logic executed by the 130, the STP 320, the SSW 420, the CSCF 530, or the MSC 620 transmits data to provide a centric service. At this time, the channel management / call distribution processor 114 stores the terminal information stored in the DBS 120 regarding information on which communication network among the first to fourth communication networks N1 to N4 is included. Based on this, the data is transmitted to the STP 320, the SSW 420, the CSCF 530, or the MSC 620.

On the other hand, when the channel management / call distribution processor 114 receives the centric service request information, the channel management / call distribution processor 114 refers to the additional service information corresponding to the terminal information stored in the DBS 120 to add between the terminals included in the same centric group. It is also possible to set the service usage range differently or set the additional service usage range for each centric group.

4 is a block diagram schematically illustrating a DBS 120 according to an embodiment of the present invention.

As shown in FIG. 4, the DBS 120 according to an embodiment of the present invention includes a database 122 and a subscriber data management processor 124.

The database 122 stores information and parameter information of terminals subscribed to the Centrix group in order to provide the Centrix service. Here, the information of the terminal means information including a telephone number and an extension number of the receiving terminal and the calling terminal corresponding to the Centrix service request information received from the calling terminal.

The subscriber data management processor 124 stores and manages various data for providing the Centrix service, that is, parameters of the terminal and additional service information in the database 122. The subscriber data management processor 124 stores the terminal information input through the system management web server and the additional service information corresponding to the terminal information in the database 122 and, if requested by the CMS 110, the database ( The information stored in 122 is reported to the CMS 110.

5 is a block diagram schematically illustrating an SES 130 according to an embodiment of the present invention.

As shown in FIG. 5, the SES 130 according to the embodiment of the present invention is implemented in plurality in order to process a plurality of service requests simultaneously received by the application server 100 without delay, and each SES 130-. 1 to 130 -N include a service logic storage unit 132 and a service execution processor 134.

The service logic storage unit 132 stores centric service logic written using an application program interface (API) for providing a centric service.

The service execution processor 134 executes the service logic corresponding to the service request information among the Centrix service logics stored in the service logic storage unit 132 according to the service request information received from the CMS 110 to the CMS 110. It passes to the included channel management / call distribution processor 114.

Meanwhile, the Centrix service system according to an exemplary embodiment of the present invention transmits a terminal B in the Centrix group (G3 in FIG. 1) including terminals accommodated in different heterogeneous communication networks among the Centrix groups shown in FIG. 1. It is possible to pull the Centrix service provided to the terminal to the terminal C, which is a terminal accommodated in a different type of communication network from the terminal B, which will be described with reference to FIG. 6.

FIG. 6 is a flowchart illustrating a process of performing a function of receiving a terminal between terminals accommodated in different heterogeneous networks through a Centrix service system according to an exemplary embodiment of the present invention. In the flowchart of FIG. 6, terminal A, terminal B, and terminal C are shown in FIG. 1, respectively, terminal A is included in the centric group G2, and terminal B and C are the terminals included in the centric group G3. . That is, terminal A and terminal B are terminals accommodated in BcN, which is the second communication network N2, and terminal C is a terminal accommodated in the third generation IP based multimedia service network, which is the third communication network N3.

First, terminal A generates a SIP message Invite message when the call connection request to the user terminal B, and transmits it to the SSW (420) (S102).

The SSW 420 confirming that the terminal B is a terminal subscribed to the Centrix service transmits the Invite message received from the terminal A to the application server 100 (S104), and the application server 100 receives the Invite message received from the terminal A. S is transmitted to the SSW 420 of the second communication network (N2) that is a communication network that the terminal B is accepted (S106).

The SSW 420 receiving the Invite message from the application server 100 transmits the Invite message to the terminal B which is the called terminal (S108), and the terminal B receiving the Invite message rings a ring tone and simultaneously rings. S180 (S110) transmits a message "180 Ring" that is a SIP message indicating that the ring (Ring Tone) ringing state (S110).

SSW 420 transmits the "180 Ring" message received from the terminal B to the application server 100 (S112), the application server 100 transmits the received "180 Ring" message to the SSW 420 ( S114). SSW 420 transmits a "180 Ring" message received from the application server 100 to the terminal A, the originating terminal (S116).

Here, step S112 is for notifying the application server 100 that the SSW 420 has executed the request for receiving the Sentence service to the receiving terminal B according to the request of the terminal A as the calling terminal. On the other hand, step S114 and S116 is for notifying the terminal A that the terminal B has received the request for the Centrix service.

When a pickup identification code for receiving a call received by the user to the terminal B is input to the terminal C, the terminal C generates an Invite message, which is a SIP message, and transmits it to the CSCF 530 (S118). In this case, the Invite message generated by the C terminal includes a pickup identification code.

The CSCF 530 transmits the Invite message received from the C terminal to the application server 100 (S120), and the channel management / call distribution processor 114 includes an Invite including a pickup identification code through the network adapter 112. Upon receiving the message, it is determined whether the terminal C is a terminal included in the centric groups G1 to G5. After confirming that the terminal C is the terminal included in the centric group G3, the channel management / call distribution processor 114 transmits the received Invite message to the SES 130. The SES 130 generates a Cancel message, which is a SIP message, to cancel the Invite message previously transmitted to the B terminal, and transmits the Cancel message to the channel management / call distribution processor 114. The channel management / call distribution processor 114 transmits a cancel message to the SSW 420 of the second communication network N2, which is a communication network through which the B terminal is accommodated, via the network adapter 112 (S122).

The SSW 420 transmits a Cancel message received from the application server 100 to the terminal B (S124), and the terminal B receiving the cancel message generates a "200 OK" signal in response to the cancel message, thereby generating the SSW ( 420).

When the SSW 420 receives a "200 OK" signal that is a response to the Cancel message from the terminal B, it transmits it to the application server 100 (S128). When the application server 100 receives the "200 OK" signal from the SSW 420, the application server 100 detects that the Cancel message transmission was successfully performed to the terminal B, and pulls the terminal C received through the CSCF 530 in step S120 In response to the Invite message including the receiving identification code, a “200 OK” signal is transmitted to the CSCF 530 (S130).

The CSSF 530 transmits a "200 OK" signal received from the application server 100 to the terminal C (S132), and the terminal C generates an ACK message, which is a SIP message, in response to the signal "200 OK". It transmits to the CSCF (530) (S134).

The CSCF 530 transmits an ACK message received from the C terminal to the application server 100 (S136), and the channel management / call distribution processor 114 transmits the ACK message received through the network adapter 112 to the SES 130. To pass). Upon receiving the ACK message, the SES 130 detects that the call connection using the Centrix service is successfully made to the C terminal, and a "200 OK" signal, which is a response signal to the Invite message transmitted by the A terminal, in step S102. And transmit it to the channel management / call distribution processor 114. The channel management / call distribution processor 114 transmits a "200 OK" signal to the SSW 420 of the second communication network N2, which is a communication network in which the A terminal is accommodated, via the network adapter 112 (S138).

The SSW 420 transmits a "200 OK" signal received from the application server 100 to the terminal A (S140), and the terminal A sends an ACK message in response to the "200 OK" signal received from the SSW 420. It generates and transmits it to the SSW (420) (S142).

The SSW 420 transmits an ACK message received from the A terminal to the application server 100 to inform that the call connection between the A terminal and the C terminal has been successfully performed (S144), and thus, between the A terminal and the C terminal. The call is made through the Centrix service.

On the other hand, A terminal accommodated in the BcN of the second communication network (N2), unlike shown in Figure 1, even if the terminal is not included in the Centrix group is pulled between the terminals accommodated in different heterogeneous networks shown in FIG. The process of performing the function is of course implemented in the same manner as described above.

As described above with reference to FIG. 6 is only an embodiment of the present invention, unlike in FIG. 6, it is possible to provide a pickup function between terminals included in the same centric group between communication networks using different heterogeneous protocols. Of course it is possible. To this end, the channel management / call distribution processor 114 according to an embodiment of the present invention is STP (320), SSW (420) included in each of the first to fourth communication network (N1 ~ N4) through the network adapter 112 ), And performs a function of translating a protocol of data transmitted / received with the CSCF 530 and the MSC 620.

On the other hand, unlike shown in Figure 1, the Centrix service system according to an embodiment of the present invention is the first to fourth communication networks (N1 ~ N4), as well as the Voice over Internet Protocol (VoIP) network Of course, it can be linked to provide the Centrix service.

As described above, the Centrix service system according to the embodiment of the present invention is compatible between different heterogeneous communication networks, thereby providing an integrated Centrix service that is not limited to the type of communication network.

Embodiments of the present invention are not implemented only through the above-described apparatus and / or method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiments of the present invention, a recording medium on which the program is recorded, and the like. Such implementations may be readily implemented by those skilled in the art from the description of the above-described embodiments.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to an aspect of the present invention, a Centrix service system that provides an integrated service that is not limited to the type of communication network may be implemented.

Claims (20)

In the Centrix service system for providing a customized Centrix service to a terminal included in the Centrix group, A call between the first terminal and the second terminal included in the second communication network in response to a request for providing a center service received from the first terminal included in the first communication network among two or more heterogeneous communication networks operated based on different protocols. A call control server providing centric services by connecting A service execution server that stores the Centrix service logic and generates and transmits the Centrix service corresponding to the request for providing the Centrix service according to the Centrix service logic to the call control server. Centrix service system comprising a. The method of claim 1, The call control server, A network adapter performing data transmission and reception with an exchange included in each of the two or more heterogeneous communication networks; The channel management / call distribution processor converts the protocol of the data to the service execution server, and converts the generated protocol of the Centrix service into a protocol suitable for the second communication network to the network adapter. Centrix service system comprising a. The method of claim 2, And a database server configured to store terminal information included in the centric group and additional service information corresponding to the terminal information. The channel management / call distribution processor, And a centric service system selectively providing the centric service based on whether the first and second terminals are terminals included in the centric group using the terminal information. The method of claim 1, The service execution server, A service logic storage unit for storing the centric service logic; A service execution processor that executes the centrix service logic corresponding to the request for providing the centrix service and delivers the same to the call control server. Centrix service system comprising a. The method of claim 4, wherein The Centrix service logic is written as an Application Program Interface (API). The method of claim 3, The database server, A database storing the terminal information and the additional service information; Subscriber data management processor for transmitting the information stored in the database to the channel management / call distribution processor in response to a request for providing information from the channel management / call distribution processor Centrix service system comprising a. The method of claim 6, The terminal information is, Centrix service system that is the telephone number and extension of the terminal included in the Centrix group. The method according to any one of claims 1 to 7, The first and second terminals are included in different centric groups. The method according to any one of claims 1 to 7, The first and second terminals are included in one centric group. The method according to any one of claims 1 to 7, The first terminal is a terminal that is not included in the centric group, and the second terminal is a terminal service system included in the centric group. The method according to any one of claims 1 to 7, The first communication network is a public switched telephone network (PSTN), and the second communication network is a wireless network (Mobile Network). The method according to any one of claims 1 to 7, The first communication network is a broadband convergence network (BcN) or a third generation IP-based multimedia service (3G-IP Multimedia Subsystem) network, and the second communication network is a public switched telephone network (PSTN) or VIO. Centrix service system, the Voice over Internet Protocol (VoIP) network. In the method of running an application server that provides a customized centric services to a plurality of terminals, a) receiving a first call connection request from the first terminal and calling a second terminal having a preset first code; b) receiving call state notification information corresponding to the call from the second terminal; c) receiving a second call connection request including the first code from a third terminal; d) making a call cancellation request to the second terminal; e) receiving a response according to the call cancellation request from the second terminal, and transmitting a response corresponding to the second call connection request to the third terminal; and f) connecting a call between the first terminal and the third terminal Method of driving an application server comprising a. The method of claim 13, Between step b) and step c), b-1) transmitting the call status notification information to the first terminal. The method of claim 13, Between step e) and step f), e-1) receiving a notification message indicating that a response corresponding to the second call connection request has been received from the third terminal; e-2) transmitting a response to the first call connection request to the first terminal in response to receiving the notification message; and e-3) receiving a notification message indicating that a response corresponding to the first call connection request has been received from the first terminal; Driving method of the application server further comprising. The method according to any one of claims 13 to 15, And the first to third terminals are included in the first to third communication networks respectively operated based on different protocols. The method of claim 16, And wherein the first communication network is a public switched telephone network (PSTN) and the second communication network is a mobile network. The method of claim 16, And the third communication network is a broadband convergence network (BcN), a third generation IP-based multimedia service (3G-IP multimedia subsystem) network, or a voice over internet protocol (VoIP) network. The method of claim 16, The first terminal is included in a first centric group, and the second and third terminals are included in a second centric group. The method of claim 16, The first terminal is a terminal that is not included in the centric group, and the second and third terminals are terminals included in the centric group.

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