KR100493528B1 - Method for Selecting Serving-Call Session Control Function in IP Multimedia Core Network - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of selecting a serving call session control server in an internet protocol multimedia service system.

2. The technical problem to be solved by the invention

In the present invention, the serving call session control in the Internet protocol multimedia service system enables the efficient use of network resources and the prevention of unnecessary network control traffic by allocating an appropriate server for the connection control to the subscriber in the Internet protocol multimedia service system environment. It is an object of the present invention to provide a method of selecting a server and a computer-readable recording medium recording a program for realizing the method.

3. Summary of the Solution of the Invention

The present invention provides a method for selecting a serving call session control server applied to an internet protocol multimedia service system, wherein a relay call session control server (I-CSCF) is connected to a home subscriber server (HSS) according to a user's multimedia service request. Authorization verification request step for requesting authority verification; A checking step of receiving a user authority verification response message from the home subscriber server (HSS) and checking whether a serving call session control server (S-CSCF) is assigned to the user; A first service registration request step of requesting service registration to the assigned serving call session control server (S-CSCF) if the serving call session control server (S-CSCF) is assigned as a result of the inspection of the checking step; If the serving call session control server (S-CSCF) is not assigned as a result of the inspection in the inspecting step, the serving call session control server according to the user share among the serving call session control server (S-CSCF) within the service registered user limit value A second service registration request step of selecting (S-CSCF) and requesting service registration from the selected serving call session control server (S-CSCF); And increasing a number of users who receive a response to a service registration request from the assigned / selected serving call session control server (S-CSCF) to increase the number of service registered users of the assigned / selected serving call session control server (S-CSCF). Including a step.

4. Important uses of the invention

The present invention is used to select a serving call session control server in an internet protocol multimedia service system.

Description

Method for Selecting Serving-Call Session Control Function in IP Multimedia Core Network} in Internet Protocol Multimedia Service System

The present invention relates to a method of selecting a serving call session control server in an internet protocol multimedia service system, and more particularly, by allocating an appropriate server for controlling a connection connection to a subscriber in an internet protocol multimedia service system environment. A method of selecting a serving call session control server in an internet protocol multimedia service system that enables prevention and efficient use of network resources, and a computer-readable recording medium having recorded thereon a program for realizing the method.

^{3GPP R5 (3 rd Generation Partnership Project} Release 5) in, in the conventional Internet protocol multimedia service system for selecting a serving call session control server (S-CSCF) of a subscriber serving call session control server (S to provide a mobile multimedia service -CSCF) only presents the data of the home subscriber server (HSS) for selection, and also because the call control server is not properly allocated to the subscriber, the subscriber is not supported for the service and the load of specific equipment. There is a problem that cannot be used efficiently because of the weight.

The present invention has been proposed to solve the above problems, and selects a serving call session control server in an internet protocol multimedia service system, which allocates an appropriate server for controlling a connection connection to a subscriber in an internet protocol multimedia service system environment. It is an object of the present invention to provide a computer-readable recording medium having recorded thereon a method and a program for realizing the method.

That is, in the Internet protocol multimedia service system environment, the present invention provides a subscriber-by-subscriber through a relay server that allows all subscribers to the network operator's subscribers or roaming subscribers currently located in the network operator's service area in order to receive multimedia services. The present invention provides a method for selecting a serving session control server in an internet protocol multimedia service system and a computer readable recording medium recording a program for realizing the method. have.

In order to achieve the above object, the present invention provides a method for selecting a serving call session control server applied to an internet protocol multimedia service system, wherein a relay call session control server (I-CSCF) is a home subscriber server according to a multimedia service request of a user. An authority verification requesting step of requesting (HSS) authority verification for the user; A checking step of receiving a user authority verification response message from the home subscriber server (HSS) and checking whether a serving call session control server (S-CSCF) is assigned to the user; A first service registration request step of requesting service registration to the assigned serving call session control server (S-CSCF) if the serving call session control server (S-CSCF) is assigned as a result of the inspection of the checking step; If the serving call session control server (S-CSCF) is not assigned as a result of the inspection in the inspecting step, the serving call session control server according to the user share among the serving call session control server (S-CSCF) within the service registered user limit value A second service registration request step of selecting (S-CSCF) and requesting service registration from the selected serving call session control server (S-CSCF); And increasing a number of users who receive a response to a service registration request from the assigned / selected serving call session control server (S-CSCF) to increase the number of service registered users of the assigned / selected serving call session control server (S-CSCF). Steps.

In addition, in the method of the present invention, a proxy call session control server (P-CSCF) receives a multimedia service request from the user and delivers it to the relay call session control server (I-CSCF) in the authorization verification request step. step; And a serving call session control server (S-CSCF) to the proxy call session control server (P-CSCF) if the response to the service registration request received in the increasing number of users is not a normal response reached within a predetermined time. Further comprising the step of notifying the unavailable state of the.

On the other hand, in the present invention, in order to select a serving call session control server, the Internet call multimedia service system having a processor, the relay call session control server (I-CSCF) according to the user's multimedia service request is the home subscriber server (HSS) Authorization verification request function for requesting authorization verification for the user; A check function for receiving a user authority verification response message from the home subscriber server (HSS) and checking whether a serving call session control server (S-CSCF) is assigned to the user; A first service registration request function for requesting service registration to the assigned serving call session control server (S-CSCF) if the serving call session control server (S-CSCF) is assigned as a result of the inspection of the inspection function; If the serving call session control server (S-CSCF) is not assigned as a result of the inspection of the inspection function, the serving call session control server according to the user share among the serving call session control server (S-CSCF) within the service registered user limit value. A second service registration request function for selecting (S-CSCF) and requesting service registration from the selected serving call session control server (S-CSCF); And increasing a number of users who receive a response to a service registration request from the assigned / selected serving call session control server (S-CSCF) to increase the number of service registered users of the assigned / selected serving call session control server (S-CSCF). A computer readable recording medium having recorded thereon a program for realizing the function is provided.

In addition, the present invention, the proxy call session control server (P-CSCF), the function of receiving the multimedia service request from the user and delivers to the relay call session control server (I-CSCF) of the authorization verification request function; And a serving call session control server (S-CSCF) to the proxy call session control server (P-CSCF) if the response to the service registration request received by the user number increasing function is not a normal response reached within a predetermined time. Provides a computer-readable recording medium having recorded thereon a program for further realizing a function of informing the state of inoperability.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary configuration of an internet protocol multimedia service system for selecting a serving call session control server of a subscriber to which the present invention is applied.

First, the visited network 10 includes user equipments (UEs) 101, 102, and 103, which are equipments that allow a user to access a network service so that a subscriber can receive a multimedia service, and an internet protocol multimedia service system. It includes a proxy session control server (P-CSCF) 104, which is the first access point in.

On the other hand, the subscribing network 11 is an access point in the operator's network, which allows a relay call session control server (I-CSCF: Interrogating-) to allow all accesses to subscribers of the network operator or roaming subscribers currently located in the service area of the network operator. Call Session Control Function (111), Serving-Call Session Control Function (S-CSCF) (112, 113, 114), which performs session control function of subscriber station, and internet protocol multimedia service subscriber. And a home subscriber server (HSS) 115 that supports mobility management functions.

User terminal (101, 102, 103), Proxy-Call Session Control Function (P-CSCF) (104), relay call session control server 111 and serving call session control servers (112, 113) 114, the session initiation protocol (SIP) 121, 122, and 123, which is a protocol for establishing, changing, or terminating a multimedia session or call, is performed.

On the other hand, between the relay call session control server (111) / serving call session control server (112, 113, 114) and the home subscriber server (HSS: Home Subscriber Server) (115) user registration status query, serving call session control server registration and Performs operations using the Diameter protocols 124 and 125 for displaying registration cancellation, network registration cancellation, incoming user location query, user profile download, user profile update by the home subscriber server, and authentication. .

FIG. 2 is a structural diagram of data of a relay call session control server (I-CSCF) and a home subscriber server (HSS) for selecting a serving call session control server according to the present invention.

First, the "identifier of the relay call session control server (I-CSCF) 20" will be described.

The relay call session control server 20 includes two identifiers, a serving call session control server service capability identifier 201 and a load sharing identifier 202, to perform an operation.

First, the serving call session control server service capability identifier 201 is an identifier for managing the service utilization capability of all serving call session control servers managed by the relay call session control server 20, and the same service as the service in the required identifier is provided. By managing the serving call session control servers using the same service group as the 'identical essential identifier service group' (2011, 2012), if there are multiple serving call session control servers having the same required identifier and different selection identifiers, the service capability It is possible to collectively manage all the serving call session control servers 112, 113, and 114 of FIG. 1 managed by the relay call session control server 20 by limiting the serving call session control server selection to one service group. Allows you to select the serving session control server more quickly.

Essential identifiers and optional identifiers of all serving call session control servers in the same essential identifier service group (2011, 2012) are basically four octet field schemes to indicate possible services for each serving call session control server (21, 22). It is designed to occupy 1 bit for each service by using, and if there are more than 32 multimedia services to be controlled by the serving call session control server, a new 4 octet field is added to allocate and manage a new service for each 1 bit.

Second, the load sharing identifier 202 may cause an overload when subscribers register services intensively through a public identifier in one serving call session control server. This is an identifier used for preventing overload and efficient load sharing. Depending on the performance and capacity of the serving session control server, the limits that can be registered by the service can be different for each user.These limits are measured by designing and managing these limits by the serving session control server. By simultaneously managing the number of service registered users, the user share of each serving call session control server can be calculated to find the serving call session control server with the least load.

The load sharing identifier 202 also manages the serving call session control server with the service groups 2021 and 2022 similar to the serving call session control server service capability identifier 201, thereby serving the serving call in the relay call session control server 20. Efficient management of internal data for session control server selection

Next, the "identifier of the home subscriber server (HSS) 23" is demonstrated as follows.

The home subscriber server (HSS) 23 includes a subscriber service capability identifier (231), a public user assigned serving call session control server identifier (232), a subscriber unassigned serving call session control server identifier (233), and a public user registration status identifier. The operation is performed by including four identifiers 234.

First, the subscriber service capability identifier 231 is an identifier for managing a multimedia service utilization capability for each subscriber. The essential identifiers and optional identifiers in the subscriber service capability identifier 231 indicate possible services of the subscribers (21, 22). To do this, as with the serving call session control server service capability identifier 201, it is basically designed to occupy one bit per service using a four octet field system, and the number of multimedia services to be controlled by the serving call session control server exceeds 32. In this case, a new 4 octet field is added to allocate and manage a new service for each 1 bit.

Second, the public user assignment serving call session control server identifier 232 is an identifier used to identify a serving call session control server that is currently registered and allocated by the user's public identifier. A serving call session control server for controlling the caller's public identifier of the user is included in the public user assigned serving call session control server identifier 232.

Third, the subscriber unassigned serving call session control server identifier 233 is an identifier for managing an unassigned identifier group of the serving call session control server that can register and use a service through a public identifier for each subscriber for call control. During registration, one of the serving call session control server identifiers in the unassigned identifier group may be selected and used as the public user assigned serving call session control server identifier 232 for the public identifier.

Fourth, the public user registration status identifier 234 is an identifier for managing a service registration for each public identifier of the user. If the public user registration status identifier 234 is registered in the public identifier of a user, the relay call session control server 20 selects the serving call session control server using the public user assignment serving session control server identifier 232. If the public user registration status identifier 234 is not registered in the user's public identifier, the relay call session control server 20 may assign the subscriber unassigned if the serving call session control server identifier 233 exists. Select the serving call session control server using the serving call session control server identifier 233, and if the subscriber unassigned serving call session control server identifier 233 does not exist, use the serving service capability identifier 231 to serve the serving call session. Select the control server.

3A to 3C are flowcharts illustrating an exemplary method of selecting a serving call session control server in an internet protocol multimedia service system according to the present invention.

First, FIG. 3A will be described. 3A illustrates a method of receiving and processing an allocated serving call session control server from a home subscriber server (HSS).

When the relay call session control server (I-CSCF) starts to drive, it requests the home subscriber server (HSS) to verify the user's authority (301). After setting and transmitting to the home subscriber server and receiving the user authority verification response message from the home subscriber server, the user authority verification response is performed (302).

In the user authority verification response process 302, it is checked whether the serving call session control server is allocated among the parameters included in the user authority verification response message (303), and if it is not assigned, it is transferred to ① ("401" in FIG. 3B). If it is allocated, after requesting registration with the session initiation protocol (SIP) to the assigned serving call session control server (304), the server waits for a response from the serving call session control server (305).

In the response waiting process 305, if a response is not received within the response time limit (i.e., when the response timer expires), the proxy session control server transmits the message to the proxy session control server, including a reason for temporarily not using the session initiation protocol. 309). If the registration response is received from the assigned serving call session control server in the Session Initiation Protocol (SIP) before the response timer expires (i.e. within the response timeout) (306), the received response message is normally It is determined whether it is received (307).

As a result of determination 307, if the received response message is not normal, it transmits to the proxy session control server, including the cause of temporarily not using the Session Initiation Protocol (SIP), and then terminates it (309).

As a result of determination 307, if the received response message is normal, the number of service registered users of the allocated serving call session control server is increased by 1 (308), and then termination processing is performed.

3B will be described below. 3B illustrates a method of receiving and processing a subscriber unassigned serving call session control server identifier of a serving call session control server service capability from a home subscriber server (HSS).

In the user authority verification response process 302, it is checked whether the serving call session control server is allocated among the parameters included in the user authority verification response message (303) (see FIG. 3A), and if not, the serving call session control server. Check whether the service capacity of the (401).

As a result of the check (401), if the serving call session control server service capability does not exist, after transmitting the data error response message of the home subscriber server to the proxy call session control server (413), the process is terminated.

As a result of the check 401, if the serving call session control server service capability exists, the process proceeds to step 402 to determine whether there is an unassigned serving call session control server identifier of the subscriber. As a result of the determination (402), if the subscriber's unassigned serving call session control server identifier does not exist, it moves to ② ("501" of FIG. 3C), and if present, the unassigned serving call session control server identifier of all subscribers is the load sharing identifier. The process proceeds to step 403 in which it is determined whether all of the service registered user thresholds of are exceeded.

As a result of the determination (403), if the unassigned serving call session control server identifiers of all subscribers exceed all of the load sharing identifier's service registration user limits, the entire unused response message is transmitted to the proxy session control server using the session initiation protocol ( 412) End processing is performed.

As a result of the determination (403), if the unassigned serving call session control server identifier of all the subscribers does not exceed the service sharing user limit of the load sharing identifier, the service registered user share among the unassigned serving call session control server identifiers of the subscriber is increased. After calculating the smallest serving call session control server identifier (404), and performing the registration request with the session initiation protocol to the calculated serving call session control server (405), the response from the calculated serving call session control server The process then transitions to waiting for step 406.

In response waiting process 406, if a response is not received within the response timeout (i.e., when the response timer expires), the remaining unassigned serving call in the subscriber's unassigned serving call session control server identifier that does not exceed the service registration user limit In step 410, it is determined whether the session control server identifier exists.

As a result of the determination of "410", if the remaining unassigned serving call session control server identifier does not exist among the unassigned serving call session control server identifiers of the subscriber, the session initiation protocol is established in the proxy session control server. After the entire unused response message is transmitted (412), the termination process is performed.

As a result of the determination of "410", if there is a remaining unassigned serving call session control server identifier among the unassigned serving call session control server identifiers of the subscribers, the unassigned serving call session control server identifier of the remaining subscribers is present. After calculating the serving call session control server identifier having the smallest service registration user share (411), the process proceeds to the process of requesting registration with the calculated serving call session control server as a session initiation protocol (405).

On the other hand, in the response waiting step 406, if a response to the registration request is received from the serving call session control server calculated within the response time limit as the session initiation protocol (407), that is, the response is received before the response waiting timer expires. If so, the process proceeds to step 408 in which it is determined whether the response message is normally received.

As a result of the determination in step 408, if the response message is not normal, determining whether there is a remaining unassigned serving call session control server identifier among the unassigned serving call session control server identifiers of the subscriber not exceeding the service registration user limit (410). After the transition to), the procedure below "410" is performed.

As a result of the determination of "408", if the response message is normal, the calculated number of service registered users of the serving call session control server is increased by 1 (409), and then termination processing is performed.

3C will be described below. 3C illustrates a method of receiving and processing a subscriber service capability identifier of a serving call session control server service capability from a home subscriber server (HSS).

In the user authority verification response process 302 of FIG. 3A, by checking whether the serving call session control server is allocated among the parameters included in the user authority verification response message (303), if the serving call session control server is not assigned, the serving If the service capability of the call session control server exists (401) and the subscriber service capability identifier (231) of the serving call session control server service capability exists (402), the service of the serving call session control server satisfying the service capability identifier of the subscriber. The process proceeds to step 501 to determine if the capability identifier exists.

If the service capability identifier of the serving call session control server that satisfies the service capability identifier of the subscriber does not exist, the data error response message of the home subscriber server is sent to the proxy session control server as a session initiation protocol. After that, the processing is terminated (512).

If the service capability identifier of the serving call session control server that satisfies the service capability identifier of the subscriber exists, the service capability identifier of the existing serving call session control server is the service registration user limit value of the load sharing identifier. The process proceeds to step 502 to determine if it is exceeded.

As a result of the determination of "502", if the service capability identifier of the existing serving call session control server exceeds all of the load sharing identifier's service registration user limits, the entire unused response message is transmitted to the proxy session control server using the session initiation protocol. 511, end processing is performed.

As a result of the determination of "502", if the service capability identifier of the existing serving session control server does not exceed the service registration user limit of the load sharing identifier, the existing serving (i.e., satisfies the service capability identifier of the subscriber). After calculating the service capability identifier of the serving session control server with the smallest share of service registration users among the service capability identifiers of the session control server (503), the server registers the session serving protocol with the calculated serving session control server. After step 504, the process transitions to step 505 of waiting for the calculated response from the serving call session control server.

In the response waiting process 505, if a response is not received within the response time limit (that is, when the response waiting timer expires), it is determined whether there is a service capability identifier of the remaining serving call session control server that satisfies the subscriber's service capability identifier. The process proceeds to step 509.

If the service capability identifier of the remaining serving call session control server that satisfies the service capability identifier of the subscriber does not exist, after transmitting the entire unused response message to the proxy session control server by the session initiation protocol (511), the determination result of " 509 " ) Exit processing.

As a result of the determination of "509", if there is a service capability identifier of the remaining serving call session control server that satisfies the service capability identifier of the subscriber, the serving call session having the smallest service registered user share among the service capability identifiers of the remaining serving call session control servers. After calculating the service capability identifier of the control server (510), the process proceeds to step 504 of requesting registration with the session initiation protocol to the calculated serving call session control server.

If a response to the registration request is received from the serving call session control server calculated within the response time limit in the response waiting process 505 (that is, a response is received before the response waiting timer expires) (506). In step 507, it is determined whether the response message is normally received.

As a result of the determination of "507", if the response message is not normal, the process proceeds to step 509 of determining whether there is a service capability identifier of the remaining serving call session control server that satisfies the service capability identifier of the subscriber, and goes below "509". Perform the process.

As a result of the determination of "507", if the response message is normal, the calculated number of service registered users of the serving call session control server is increased by one (508), and then the termination process is performed.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains, and the above-described embodiments and accompanying It is not limited by the drawings.

In the present invention as described above, in the Internet protocol multimedia service system environment, a relay call session control server that allows a subscriber to access all of the network operator's subscribers or roaming subscribers currently located in the service area of the network operator in order to receive multimedia services. By assigning the appropriate serving call session control server for the call connection control for each subscriber through the service registration, there is an excellent effect to efficiently use network resources and to prevent unnecessary network control traffic.

1 is an exemplary configuration of an internet protocol multimedia service system for selecting a serving call session control server of a subscriber to which the present invention is applied.

FIG. 2 is an exemplary structural diagram of data of a relay call session control server (I-CSCF) and a home subscriber server (HSS) for selecting a serving call session control server according to the present invention; FIG.

3A to 3C are flowcharts illustrating an exemplary method for selecting a serving call session control server in an internet protocol multimedia service system according to the present invention;

* Explanation of symbols on the main parts of the drawing

10: Visit Network 11: Join Network

101 to 103: user terminal 111: relay call session control server

112 to 114: Serving call session control server 115: Home subscriber server

Claims (12)

A method for selecting a serving call session control server applied to an internet protocol multimedia service system, An authorization verification request step of requesting authorization of the user to the home subscriber server (HSS) by a relay call session control server (I-CSCF) according to a multimedia service request of the user; A checking step of receiving a user authority verification response message from the home subscriber server (HSS) and checking whether a serving call session control server (S-CSCF) is assigned to the user; A first service registration request step of requesting service registration to the assigned serving call session control server (S-CSCF) if the serving call session control server (S-CSCF) is assigned as a result of the inspection of the checking step; If the serving call session control server (S-CSCF) is not assigned as a result of the inspection in the inspecting step, the serving call session control server according to the user share among the serving call session control server (S-CSCF) within the service registered user limit value A second service registration request step of selecting (S-CSCF) and requesting service registration from the selected serving call session control server (S-CSCF); And An increase in number of users that receives a response to a service registration request from the assigned / selected serving call session control server (S-CSCF) to increase the number of service registered users of the assigned / selected serving call session control server (S-CSCF); Serving call session control server selection method in the Internet protocol multimedia service system comprising a. The method of claim 1, A proxy session control server (P-CSCF) receiving a multimedia service request from the user and forwarding the multimedia service request to the relay call session control server (I-CSCF) in the authorization verification request step; And If the response to the service registration request received in the increasing number of users is not a normal response reached within a predetermined time, the proxy call session control server (P-CSCF) of the serving call session control server (S-CSCF) Steps to Notify Serving call session control server selection method in the Internet protocol multimedia service system further comprising. The method according to claim 1 or 2, The second service registration request step, If the serving call session control server (S-CSCF) is not assigned as a result of the inspection in the inspecting step, serving that is not allocated using the subscriber unassigned serving call session control server identifier according to the serving call session control server service capability existence A first checking step of checking whether a call session control server (S-CSCF) exists; As a result of the checking in the first checking step, if there is an unassigned serving call session control server (S-CSCF), the service registration user limit using a load sharing identifier among the unassigned serving call session control server (S-CSCF) Selecting a first serving call session control server (S-CSCF) having a smallest user share and having the smallest user share, and requesting service registration from the selected first serving call session control server using a session initiation protocol (SIP); And If the S-CSCF does not exist as a result of confirming the first verification step, a serving call session having a service capability using a subscriber service capability identifier and a serving call session control server service capability identifier The second serving call session control server (S-CSCF) is searched, and the second serving call session control server (S-CSCF) having the smallest user occupancy within the service registered user limit using the load sharing identifier among the searched serving call session control servers (S-CSCF). -CSCF) and requesting service registration to the selected second serving call session control server (S-CSCF) using a session initiation protocol (SIP). Serving call session control server selection method in the Internet protocol multimedia service system comprising a. The method of claim 3, wherein The first checking step, A second confirmation step of confirming whether a serving call session control server service capability is present using a serving call session control server service capability identifier if the serving call session control server (S-CSCF) is not assigned as a result of the inspection of the inspection step; As a result of confirming the second verification step, if there is a serving call session control server service capability, confirming whether an unassigned serving call session control server (S-CSCF) exists by using a subscriber unassigned serving call session control server identifier. ; And As a result of the confirmation of the second verification step, if there is no serving call session control server service capability, a home subscriber server data error response message is transmitted to the proxy call session control server (P-CSCF) using a session initiation protocol (SIP). step Serving call session control server selection method in the Internet protocol multimedia service system comprising a. The method of claim 4, wherein The inspection process of the serving call session control server (S-CSCF) allocation of the inspection step, A method for selecting a serving call session control server in an internet protocol multimedia service system, characterized by checking using a subscriber service capability identifier. The method of claim 5, The serving call session control server (S-CSCF) selection process, Preferentially selecting a serving call session control server (S-CSCF) having a small user share until a normal response to a service registration request is received from the selected serving call session control server (S-CSCF) within a predetermined time. A method for selecting a serving call session control server in an internet protocol multimedia service system. The method of claim 6, The serving call session control server service capability identifier is Serving call session control servers which are classified into a required identifier and an optional identifier and are provided with the same essential identifier are collectively managed by the serving call session control servers supporting the same service. Each of the required identifier and the optional identifier provides a service that can be supported using a 4-octet field system. Serving call session control server selection method in the Internet protocol multimedia service system, characterized in that for displaying. The method of claim 6, The load sharing identifier, Serving call session control servers supporting the same service are classified and managed in the same group, and serving call session control in an internet protocol multimedia service system characterized by managing user limits and number of service registered users for each serving call session control server. How to choose a server. The method of claim 6, The subscriber service capability identifier is An identifier for managing a service capability for each subscriber, which is classified into a required identifier and a selection identifier, and each of the required identifier and the selection identifier indicates a possible service of subscribers using a 4-octet field system. How to select Serving Call Session Control Server in system. The method of claim 6, The subscriber unassigned serving call session control server identifier is A method of selecting a serving call session control server in an internet protocol multimedia service system, characterized by indicating an unassigned serving call session control server that can register and use a service. In order to select the serving session control server, Internet protocol multimedia service system having a processor, An authorization verification request function for requesting authorization of the user from the home subscriber server (HSS) by the relay call session control server (I-CSCF) according to the multimedia service request of the user; A check function for receiving a user authority verification response message from the home subscriber server (HSS) and checking whether a serving call session control server (S-CSCF) is assigned to the user; A first service registration request function for requesting service registration to the assigned serving call session control server (S-CSCF) if the serving call session control server (S-CSCF) is assigned as a result of the inspection of the inspection function; If the serving call session control server (S-CSCF) is not assigned as a result of the inspection of the inspection function, the serving call session control server according to the user share among the serving call session control server (S-CSCF) within the service registered user limit value. A second service registration request function for selecting (S-CSCF) and requesting service registration from the selected serving call session control server (S-CSCF); And Receiving a response to a service registration request from the assigned / selected serving call session control server (S-CSCF) to increase the number of service registered users of the assigned / selected serving call session control server (S-CSCF) A computer-readable recording medium having recorded thereon a program for realizing this. The method of claim 11, A proxy session control server (P-CSCF) that receives a multimedia service request from the user and delivers the multimedia service request to the relay call session control server (I-CSCF) of the authority verification request function; And If the response to the service registration request received by the user number increasing function is not a normal response reached within a predetermined time, the proxy call session control server (P-CSCF) of the serving call session control server (S-CSCF) Ability to notify you of inability A computer-readable recording medium that records a program for further realization.