KR102098216B1 - Method and apparatus for deterimining call process, and systems for call process - Google Patents

Abstract

The present invention relates to a method and apparatus for determining call processing, and an apparatus for processing the call. The disclosed call processing decision method includes extracting an identifier included in the call connection request message, determining whether it is a CSFB call based on the extracted identifier, and determining the result when the processing of the call connection request message fails. Accordingly, the CSFB call determines call termination, and the non-CSFB call includes determining call connection reprocessing through the circuit switched network. Accordingly, when the called mobile communication terminal apparatus of the generated call is in a call by SRVCC handover, the circuit network switching node transmits a call connection message to the IMS switching node for control of the additional service, and the IMS switching node is a circuit switching network. An infinite loop of call processing that may occur when a call connection message is transmitted for reprocessing through is inherently prevented and does not occur.

Description

METHOD AND APPARATUS FOR DETERIMINING CALL PROCESS, AND SYSTEMS FOR CALL PROCESS}

The present invention provides a method and apparatus for determining a subsequent call processing method when a call processing failure occurs when the called mobile communication terminal device of the generated call is in a call by SRVCC (Single Radio Voice Call Continuity) handover. It relates to a call processing system for performing a call processing method according to the decision.

As is well known, 3GPP Release 8 describes an Evolved Packet Core (EPC), which is a network architecture, as one of the mobile communication systems. EPC is a set of network nodes for 3GPP Long Term Evolution (LTE) system. EPC has evolved the core network of the existing 3GPP system architecture to support Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN), which is an evolved RAN, and also increases the efficiency of the packet network. In order to simplify the network node, it has an efficient network structure. A wireless communication system including EPC and E-UTRAN may be referred to as an Evolved Packet System (EPS), and the LTE mobile communication system currently being serviced in Korea corresponds to this.

On the other hand, in the early stage of building an LTE mobile communication system, a mixed communication environment with a legacy network such as a WCDMA mobile communication system appears, and in this communication environment, WCDMA (Wideband Code Division Multiple Access) network, etc. can be used while being able to access the LTE network. A dual mode mobile communication terminal device capable of accessing the same legacy network may be operated. In addition, at the beginning of the LTE mobile communication service, a WCDMA mobile communication system was used to provide a voice call service to a dual mode mobile communication terminal device, and an LTE mobile communication system was used to provide a data communication service.

Unlike this, the VoLTE service uses an LTE mobile communication system as well as data communication as well as voice calls. This VoLTE service is also called a high definition (HD) voice service. According to the VoLTE service, it is possible to provide a clearer HD-class voice call service during a voice call, and users can share content such as maps, music, news, photos, etc. while showing a screen like a counterpart in real time during a call. .

However, since the service area of the LTE network is limited at present, there is a problem in that the continuity of a voice call is not guaranteed in an area where the propagation environment is poor, such as outside the limited area or a service cell border area. In order to solve this problem, there is a trend to provide voice call continuity in conjunction with a circuit switched network. At this time, a single radio voice call continuity (SRVCC) function is provided to provide continuity with one radio resource so that the mobile communication terminal device does not need to access all of the radio resources provided by the packet switched network and the circuit network. SRVCC is a technology that handovers voice traffic to a circuit network to provide call continuity when entering the LTE weak field during VoLTE calls.

On the other hand, in order to provide a satisfactory VoLTE service for the user, it is important to provide a service with a clean sound quality after a call connection between the calling party and the called party is made, but above all, a high incoming success rate must be provided. To this end, when the VoLTE call fails, the call is retried through the circuit network of the legacy network, and this is called CSFB (Circuit Switched Fallback) call processing.

However, in the case of a CSFB call that occurs when the called mobile communication terminal device is in a call by SRVCC handover, if the call processing fails due to any reason when the IMS (IP Multimedia Subsystem) switching node processes the call related to the supplementary service, the circuit There is a problem in that reprocessing through a network is repeatedly performed.

The infinite loop generated by the circuit network reprocessing will be described in more detail as follows.

When the mobile communication terminal device A and the mobile communication terminal device B request a call connection with the mobile communication terminal device A while the call is connected and the call is connected by SRVCC handover, the mobile communication terminal device A is a legacy network. Because it is registered in the circuit network, the call connection request message is transmitted to the Media Gateway Control Function (MGCF) through the IMS network.

Then, the MGCF queries the location of the mobile communication terminal device A to deliver a call to the MSC server (Mobile Switching Center Server), and the MSC server calls the CSMS (Call Session Control Function), an IMS exchange node, for control of additional services. , And the CSCF sends an additional service control request message to a Telephony Application Server (TAS).

At this time, if an instantaneous failure occurs in the TAS, a call processing failure occurs in which the CSCF cannot transmit an additional service control request message, and the CSCF attempts an independent call.

Here, the CSCF determines that the mobile communication terminal device A is located in the LTE network, and attempts to receive a call through a Serving Gateway (SGW), but the mobile communication terminal device A is located in a circuit network, so a call reception failure occurs. Then, the CSCF decides to reprocess the call through the circuit network according to the incoming call failure, and sends a call connection request message to the MGCF.

Then, as described above, the MGCF queries the location of the mobile communication terminal device A to deliver the call to the MSC server, the MSC server delivers the call to the CSCF for control of the additional service, and the CSCF requests the TAS to control the additional service. Send a message. In this way, an infinite loop is generated by reprocessing the circuit network.

Republic of Korea Patent Publication No. 10-2012-0095897, date of publication August 29, 2012.

According to an embodiment of the present invention, when the called mobile communication terminal device of the generated call is busy by SRVCC handover, the circuit network switching node transmits a call connection request message including an identifier indicating the CSFB call to the IMS switching node. The IMS switching node terminates the call for the CSFB call without reprocessing through the circuit switching network even if a call processing failure occurs.

The problem to be solved of the present invention is not limited to those mentioned above, and another problem to be solved that is not mentioned will be clearly understood by a person having ordinary knowledge to which the present invention belongs from the following description.

The method for determining call processing according to an aspect of the present invention includes: extracting an identifier included in a call connection request message; determining whether it is a CSFB call based on the extracted identifier, and for the call connection request message. Upon failure of processing, the CSFB call determines call termination according to the result of the determination, and the non-CSFB call may include determining call connection reprocessing through a circuit switched network.

The apparatus for determining call processing according to another aspect of the present invention includes an extraction unit for extracting an identifier included in a call connection request message, a determination unit for determining whether it is a CSFB call based on the extracted identifier, and the call connection request message When it is determined that the CSFB call is determined based on the identifier when the processing of the call fails, the determination unit may include a decision unit for determining call connection re-processing through the circuit switched network if it is determined that the call is not the CSFB call.

A call processing system according to another aspect of the present invention includes a circuit network switching node that transmits a call connection request message including an identifier indicating a CSFB call when the called mobile communication terminal device is in a call by SRVCC handover, Based on the identifier included in the call connection request message received from the circuit network switching node, it is determined whether it is a CSFB call, and when the call processing fails for the call connection request message, the CSFB call is The termination process, and the non-CSFB call may include an IMS exchange node that re-processes the call connection through the circuit switched network.

According to an embodiment of the present invention, the IMS switching node terminates the call for the CSFB call without reprocessing through the circuit switching network even if a call processing failure occurs.

Accordingly, when the called mobile communication terminal device of the generated call is busy by SRVCC handover, the circuit network switching node transmits a call connection message to the IMS switching node for control of the additional service, and the IMS switching node establishes the circuit switching network. Infinite loop of call processing, which may occur when a call connection message is transmitted for re-processing through, has an effect of being fundamentally prevented.

1 is a network configuration diagram of a mobile communication service system that can employ a call processing decision apparatus according to an embodiment of the present invention.
2 is a detailed configuration diagram of a call processing decision apparatus according to an embodiment of the present invention.
3 is a flowchart illustrating a call processing method according to application of a call processing determination method according to an embodiment of the present invention.
4 is a flowchart illustrating a CSFB call processing process by a call processing system and a mobile communication service system employing a call processing determination apparatus according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to completely inform the person having the scope of the invention, and the present invention is only defined by the scope of the claims.

In describing embodiments of the present invention, when it is determined that a detailed description of known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

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

1 is a network configuration diagram of a mobile communication service system that can employ a call processing decision apparatus according to an embodiment of the present invention. 1 illustrates a case where the WCDMA mobile communication network is operated as a legacy network, but the legacy network is not limited thereto. For example, other asynchronous mobile communication networks such as GSM (Global System for Mobile) or other synchronous mobile communication networks such as CDMA2000 may be used together with the LTE mobile communication network.

As shown in this, the mobile communication terminal device (Mobile Equipment) 300 can be operated in a mixed environment of legacy networks such as an LTE mobile communication network providing packet-based voice services and a WCDMA mobile communication network providing circuit-based voice services. The mobile communication terminal device 300 is a service of the NodeB 210 in which the service area 111 of the eNodeB 110 serving as a base station constituting the LTE mobile communication network serves as a base station constituting a WCDMA mobile communication network. It may be operated in a service overlapping region included in the region 211. The mobile communication terminal device 300 is located in any one of a plurality of cells existing in the service area 111 of the eNodeB 110 to receive a mobile communication service. For example, the mobile communication terminal device 300 may be implemented in various forms, such as a smart phone, a notepad, and a tablet computer.

eNodeB 110, Mobility Management Entity (MME) 120, Home Subscriber Server (HSS) 130, Serving Gateway (SGW) 140, Packet Data Network Gateway (PGW) 150, Policy & Charging Rule Function) 160 may constitute an LTE mobile communication network.

The eNodeB 110 communicates with the mobile communication terminal device 300 to serve as a base station to ensure mobility. The eNodeB 110 includes radio bearer control, radio admission control, connection mobility control, dynamic resource allocation to the mobile communication terminal device 300, and the like. Performs the same radio resource management function. In addition, IP header compression and decryption of user data streams, routing of user plane data to SGW 140, scheduling and transmission of paging messages, scheduling and transmission of broadcast information, Measurement and measurement reporting settings for mobility and scheduling are performed.

In addition, the eNodeB 110 is handed over so that the mobile communication terminal device 300 can establish a call by accessing a wireless access network that provides a relatively superior voice call quality among the eNodeB 110 and the NodeB 210. Can decide. In particular, it is possible to determine the handover of the VoLTE call from the packet switching domain to the circuit switching domain based on the electric field measurement report provided from the mobile communication terminal device 300.

The MME 120 is responsible for signal control between the eNodeB 110 and the SGW 140, and determines routing for transmission data of the mobile communication terminal device 300. The MME 120 performs paging message distribution to the eNodeB 110, NAS (Non Access Spectrum) signaling, intra-network handover control, and tracking area list management. In addition, the MME 120 performs selection of the SGW 140 and the PGW 150, selection and change of the MME 120 for handover, and terminal authentication. The MME 120 is a mobile communication terminal device 300 or other network node, such as processing a control signal when there is a combination request from a PGW 150 or SGW 140 or a radio bearer setup request. It is responsible for various functions of the control plane, and receives subscriber profile information, authentication, and location-related data from the HSS 130 to establish and move the EPS packet bearer (Evolved Packet System bearer) or IP tunnel (IP tunnel). It performs functions such as mobility management.

The HSS 130 is a network node including a database that contains subscriber information for the LTE mobile communication network, and stores subscriber profile information, authentication, and location related data.

The SGW 140 is a user plane node that performs session control to process payload traffic according to the established session. Interworking with the eNodeB 110 and the S1-U interface, it supports handoff in 3GPP, sets the PGW 150 and the EPS bearer, and transmits a PDU (Packet Data Unit) using tunneling. The SGW 140 selects the PGW 150 based on the subscriber profile, and in the case of an inbound roaming call, generates charging data for mutual settlement with the PGW of the home network.

The PGW 150 is a user plane node that allocates the IP of the mobile communication terminal device 300 and performs session control interworking with an external Internet network and a non-3GPP network. For packet service, SGW 140 and external network maintain routing information, and perform tunneling and IP routing functions. In addition, PDUs are delivered to the SGW 140 and the external network. The PGW 150 performs charging processing in the case of a local call.

The PCRF 160 provides dynamic QoS (Quality of Service) and charging rules according to service data flow, and performs communication policy and charging processing in the communication network.

NodeB 210, Radio Network Controller (RNC) 220, Serving General packet radio service Support Node (SGSN) 230, Mobile Switching Center (MSC) 240, Home Location Register (HLR) 250, CGS (Cellular Gateway Switch) 260, GGSN (Gateway General packet radio service Support Node) 270, MSC server 280, SMSC (Short Message Service Center) 290, etc. may constitute a WCDMA mobile communication network. Here, the NodeB 210 and the RNC 220 correspond to a radio access network area, the MSC 240 and the CGS 260 correspond to a circuit switched core network, and the SGSN 230 and GGSN 270 exchange packets. Corresponds to the core network.

The NodeB 210 secures a frequency used for connection with the mobile communication terminal devices 300 and ensures a stable connection with the mobile communication terminal devices 300.

The RNC 220 controls a plurality of NodeBs 210, allocates communication resources to each NodeB 210, and is responsible for functions such as handover.

The SGSN 230 is connected to various RNCs 220 and is in charge of mobility and packet session management of the mobile communication terminal device 300, can perform IP routing, and register location of the mobile communication terminal device 300 and You can do the same interaction.

In particular, the SGSN 230 is the mobile communication terminal device 300 after the SRVCC handover from the packet switched domain to the circuit switched domain, the packet exchange path RNC 220 and NodeB 210 according to the request of the SMSC 290 Send a short message to the mobile communication terminal device 300 through.

The MSC 240 stores visitor location information, receives subscriber profile information, authentication, and location related data from the HLR 250 and performs switching control for voice communication. When the preparation for SRVCC handover of the VoLTE call is requested from the MSC server 280, the MSC 240 requests the RNC 220 of the radio access network area to reset the location for the SRVCC handover, and from the RNC 220 When the location reset completion message is received, the MSC server 280 is notified that the SRVCC handover is completed.

The HLR 250 is a network node including a database including subscriber information for a WCDMA mobile communication network, and stores subscriber profile information, authentication and location related data.

The CGS 260 acts as a gateway connecting the WCDMA mobile communication network and the general communication network to enable communication with other communication systems connected to the general communication network, and serves as a gateway between the MSC 240 and the IMS.

The GGSN 270 serves as a gateway to connect the IP network and the PS domain of the WCDMA network by directly connecting to the IP network, maintaining routing information between the SGSN 230 and the external network, and tunneling and IP routing. Perform a function.

The MSC server 280 is a circuit network switching node and provides session data protocols for voice and video for SRVCC function by the SCC AS 470. When the MME 120 requests a handover from the packet switched domain to the circuit switched domain for the VoLTE call, the MSC server 280 requests handover preparation to the circuit switched core network of the legacy WCDMA mobile communication network. When a response to the preparation of the over is received, a session forwarding start message for SRVCC handover is transmitted to the IMS after circuit connection with the MSC 240.

Particularly, when the mobile communication terminal device 300 of the called party is in a call by SRVCC handover, the MSC server 280 connects the call to the mobile communication terminal device 300 in a call registered in the circuit network. If a message needs to be transmitted to the CSCF (Call Session Control Function) 410, an identifier indicating the CSFB call is additionally included in the call connection request message and transmitted.

The SMSC 290 provides a short message service to the mobile communication terminal device 300. The SMSC 290 provides a short message service through a circuit switched domain according to a general service flow.

CSCF 410, HLR 420, Media Gateway (MGW) 430, Media Gateway Control Function (MGCF) 440, Telephony Application Server (TAS) 450, Multimedia Resource Function (MRF) 460, The SCC Service Centralization and Continuity Application Server (AS) 470 may configure IMS.

Here, the TAS 450 and the SCC AS 470 are servers for providing individual application services. The TAS 450 and the SCC AS 470 may be combined into one server, and may be referred to as an application server (AS). One AS can provide all application service functions, and multiple AS can provide application service functions according to each function.

Then, among the nodes constituting the IMS, the CSCF 410 may be equipped with a call processing decision device (reference numeral 500 in FIG. 2) according to an embodiment of the present invention or may interwork with a separately installed call processing decision device. In addition, the TAS 450 may be equipped with a call processing determination device (reference numeral 500 in FIG. 2) according to an embodiment of the present invention or may interwork with a separately installed call processing determination device. Hereinafter, a case where a call processing determination device (reference numeral 500 in FIG. 2) according to an embodiment of the present invention is mounted on the CSCF 410 will be exemplified.

CSCF 410 is an IMS exchange node that performs call processing, and is an infrastructure system that performs basic functions for multimedia session control based on Session Initiation Protocol (SIP). The CSCF 410 processes subscriber registration, authentication, charging, triggering and routing for each service, callee location inquiry, and compression and decompression of SIP messages, and can be divided into Proxy_CSCF, Interogating-CSCF, and Serving-CSCF according to the role.

In particular, the CSCF 410 transmits an additional service control request message to the TAS 450 when the MSC server 280 transmits a call connection request message for CSFB call processing. At this time, if the instantaneous failure occurs in the TAS 450 and a call processing failure occurs, the CSCF attempts an independent call. First, when an incoming call fails through an LTE network, a call connection request message is transmitted to the MGCF 440 by determining re-processing of the call through the circuit network. However, for a CSFB call, even if a call processing failure occurs due to an instantaneous failure of the TAS 450, the call is terminated without reprocessing the call through the circuit network. Then, the MSC server 280 can be informed of the call termination process. To this end, the CSCF 410 determines whether it is a CSFB call based on the identifier included in the call connection request message received from the MSC server 280, which is a circuit network switching node, and when call processing fails for the call connection request message The CSFB call is terminated, and the non-CSFB call reprocesses the call connection through the circuit switched network.

The HLR 420 is a network node including a database including subscriber information for a WCDMA mobile communication network and / or LTE mobile communication network, and stores subscriber profile information, authentication, and location related data.

The MGW 430 is a gateway that serves as a gateway between the MGCF 440 and the CGS 260, and converts signaling and media for interworking with the LTE mobile communication network and the WCDMA mobile communication network connected to the CSCF 410.

The MGCF 440 performs signal conversion for interworking with PSTN, ISUP (ISDN User Part), and WCDMA used in SIP and circuit-switched networks, and controls the MGW 430. That is, protocol conversion is performed between the legacy network and the IMS call control protocol. For example, the MGCF 440 may convert a signal for a call coming from the WCDMA to the IMS and transfer it to the CSCF 410.

The TAS 450 is a telephony server that provides a telephony service, and provides additional services such as caller ID service, call / prohibition, and call forwarding. The TAS 450 is a group video call service, intelligent network prepaid billing processing, billing information transmission, control of the right to speak when performing a PTT (Push-To-Talk) function, announcement, ring-back-tone function It is a device for providing various application services.

The MRF 460 acts as a media server that provides media sources on the IMS. In addition, the MRF 460 manages call guidance broadcasting (voice / video) provided to the mobile communication terminal device 300, mixing streams for multi-party group video calls, conversion between text and voice / voice recognition, multimedia It can operate as a multimedia server for real-time transcoding of data.

The SCC AS 470 provides an SRVCC function that provides continuity with one radio resource so that the mobile communication terminal device 300 does not need to access all of the radio resources provided by the packet network and the circuit network. For example, when entering the LTE weak field during a VoLTE call, voice traffic is handed over to the circuit network to provide call continuity. When the session forwarding message for SRVCC handover of the VoLTE call is received from the MSC server 280, the SCC AS 470 performs a session forwarding procedure according to the session forwarding start message, and the IMS access leg for the packet switched domain Release it.

The HSS 130, HLR 250, and HLR 420 shown in FIG. 1 are subscriber data management devices including a database containing subscriber information for a WCDMA mobile communication network and an LTE mobile communication network, as illustrated They may be operated separately, or may be integrated into one node or two nodes. For example, the HLR 250 and the HSS 130 are integrated into a single subscriber data management device, and the HLR 420 may be interlocked while being installed separately from them.

2 is a detailed configuration diagram of a call processing decision apparatus 500 according to an embodiment of the present invention. The call processing determination apparatus 500 may be mounted on the CSCF 410 or the TAS 450 illustrated in FIG. 1, or may be interlocked with the CSCF 410 or the TAS 450 in a separately installed state.

As shown in this, the call processing determination apparatus 500 according to the embodiment of the present invention includes an extraction unit 510, a determination unit 520, a determination unit 530, and the like.

The extraction unit 510 extracts the identifier included in the call connection request message and provides it to the determination unit 520. For example, the call connection request message may include an identifier indicating a CSFB call when the called mobile communication terminal device is in a call by SRVCC handover.

The determination unit 520 determines whether the call is a CSFB based on the extracted identifier. For example, the determination unit 520 may determine the CSFB call when indicating that the identifier extracted by the extraction unit 510 is a CSFB call. Alternatively, when a specific identifier exists in the call connection request message, it may be determined as a CSFB call unconditionally.

The decision unit 530 determines that the CSFB call is terminated when the call connection request message is not processed, and the non-CSFB call reprocesses the call connection through the circuit switched network.

3 is a flowchart illustrating a call processing method according to application of a call processing determination method according to an embodiment of the present invention.

As shown in this, in the call processing method according to the embodiment of the present invention, when the called mobile communication terminal device is in a call by SRVCC handover, the IMS switching node circuits the call connection request message including the identifier indicating the CSFB call. And receiving from the network switching node (S610).

Further, after confirming whether the IMS switching node includes the identifier indicating the CSFB call in the call connection request message, the method further includes attempting to transmit an additional service control request message to the telephony server (S620, S630).

In addition, after the call processing for the call connection request message, that is, after the transmission of the additional service control request message, waiting for receiving the additional service control response message from the telephony server (S640, S680).

In addition, the step of determining whether the IMS switching node is a CSFB call based on the identifier included in the call connection request message (S650).

In addition, when the IMS switching node processes the call connection request message, that is, when the transmission of the additional service control request message fails, the CSFB call is terminated, and the non-CSFB call reprocesses the call connection through the circuit switched network (S660). , S670).

4 is a flowchart illustrating a CSFB call processing process by a call processing system and a mobile communication service system employing a call processing determination apparatus according to an embodiment of the present invention.

Hereinafter, a process of processing a CSFB call during a call by SRVCC handover of a VoLTE call according to an embodiment of the present invention will be described in more detail with reference to FIGS. 1 to 4. In the following description, the mobile communication terminal device 300 is divided into a mobile communication terminal device A, a mobile communication terminal device B, and a mobile communication terminal device C, and the description is omitted.

First, it is premised that the mobile communication terminal device A and the mobile communication terminal device B are connected by SRVCC handover and are on a call.

When the mobile communication terminal device C requests a call connection with the mobile communication terminal device A in such a busy situation, the mobile communication terminal device A is registered in the circuit network of the legacy network, so the call to the MGCF 440 through the IMS network. A connection request message is transmitted (703).

Then, the MGCF 440 transmits a routing information request message to the HLR 240 in order to query the location of the mobile communication terminal device A (705).

Subsequently, the HLR 250 transmits a message for requesting an internal network identification number of the mobile communication terminal device A to the MSC server 280 (707), and the MSC server 280 sends an internal network identification message to the HLR 250. Send (709).

Then, the HLR 250 transmits a routing information response message to the MGCF 440 (711), and the MGCF 440 that completes the location inquiry of the mobile communication terminal device A sends the initial address message (initial) to the MSC server 280. address message) to request a call connection.

Then, the MSC server 280 forwards the call to the CSCF 410 for control of the additional service to which the mobile communication terminal device A is subscribed. At this time, the MSC server 280 transmits 715 a CSFB identifier indicating that the current call is a CSFB call by adding a call connection request message, thereby allowing the CSCF 410 to determine the CSFB call.

The CSCF 410 receiving the call connection request message from the MSC server 410 (S610) checks whether the CSFB identifier is included in the call connection request message (S620), and then controls the additional service to the TAS 450. A request message is transmitted (717).

Here, the extraction unit 510 of the call processing determination apparatus 500 mounted on the CSCF 410 extracts the CSFB identifier included in the call connection request message and provides it to the determination unit 520.

Then, the determination unit 520 of the call processing determination apparatus 500 determines whether the currently requested connection request is a CSFB call based on the extracted CSFB identifier. For example, the determination unit 520 may determine the CSFB call when indicating that the CSFB identifier extracted by the extraction unit 510 is a CSFB call. Alternatively, when a specific identifier exists in the call connection request message, it may be determined as a CSFB call unconditionally.

However, when the CSCF 410 performs call processing to send the TAS 450 an additional service control request message, if an instantaneous failure occurs in the TAS 450, the CSCF 410 does not transmit the additional service control request message. An unsuccessful call processing failure occurs (S640).

In this way, when a call processing failure occurs, the call processing determination device 500 mounted on the CSCF 410 determines a subsequent call processing method. That is, the decision unit 530 of the call processing decision apparatus 500 determines that the CSFB call terminates the call, and the non-CSFB call determines reconnection of the call through the circuit switched network. In the embodiment of FIG. 4, the call termination is determined because it is a CSFB call.

Then, the CSCF 410 terminates the call (S660) without retrying the call processing through the circuit switched network.

Then, the CSCF 410 may inform the MSC server 280 of the call termination process (719).

Meanwhile, when the additional service control request message in step S630 is normally transmitted, the CSCF 410 waits for the additional service control response message from the TAS 450 to be received (S680). Also, unlike the embodiment of FIG. 4, if the call that failed in step S640 is not a CSFB call, the CSCF 410 reprocesses the call through the circuit network (S670). That is, the CSCF 410 attempts an independent call, and after a call failure occurs through the LTE network, re-processing of the call through the circuit network is determined and a call connection request message will be transmitted to the MGCF 440.

As described so far, according to the embodiment of the present invention, even if the CSCF 410, which is an IMS switching node, encounters a call processing failure situation, the CSFB call is terminated without reprocessing through the circuit switching network.

Accordingly, when the called mobile communication terminal device of the generated call is busy by SRVCC handover, the circuit network switching node transmits a call connection message to the IMS switching node for control of the additional service, and the IMS switching node establishes the circuit switching network. The infinite loop of call processing, which may occur when transmitting a call connection message for re-processing through, is basically prevented and does not occur.

Combinations of each block in the block diagrams and respective steps in the flowcharts attached to this specification may be performed by computer program instructions. These computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, so that instructions executed through a processor of a computer or other programmable data processing equipment may be used in each block or flowchart of the block diagram. In each step, means are created to perform the functions described. These computer program instructions can also be stored in computer readable or computer readable memory that can be oriented to a computer or other programmable data processing equipment to implement a function in a particular way, so that computer readable or computer readable memory The instructions stored in it are also possible to produce an article of manufacture containing instructions means for performing the functions described in each step of each block or flowchart of the block diagram. Since computer program instructions may be mounted on a computer or other programmable data processing equipment, a series of operational steps are performed on the computer or other programmable data processing equipment to create a process that is executed by the computer to generate a computer or other programmable data. It is also possible for instructions to perform processing equipment to provide steps for executing the functions described in each block of the block diagram and in each step of the flowchart.

Further, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function (s). It should also be noted that in some alternative embodiments it is also possible that the functions mentioned in blocks or steps occur out of order. For example, two blocks or steps shown in succession may in fact be executed substantially simultaneously, or it is also possible that the blocks or steps are sometimes performed in reverse order depending on the corresponding function.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical thoughts within the equivalent range should be interpreted as being included in the scope of the present invention.

According to an embodiment of the present invention, even if an IMS switching node encounters a call processing failure, the CSFB call is terminated without reprocessing through the circuit switching network.

Therefore, when the called party's mobile communication terminal apparatus of the generated call is busy by SRVCC handover, the circuit network switching node transmits a call connection message to the IMS switching node for control of the additional service, and the IMS switching node establishes the circuit switching network. The infinite loop of call processing, which may occur when transmitting a call connection message for re-processing through, is basically prevented and does not occur.

The present invention can be used in a heterogeneous mobile communication system in which the LTE mobile communication network is operated together with various legacy networks.

410: CSCF 470: TAS
500: call processing determination device 510: extraction unit
520: discrimination unit 530: determination unit

Claims (5)

A call processing determination method of a call processing determination apparatus,
Identifier included in the call connection request message-The identifier indicating a CSFB (Circuit Switched Fallback) call when the called mobile communication terminal device of the call connection request message is in a call by SRVCC (Single Radio Voice Call Continuity) handover is Include in the call connection request message-extracting,
Determining whether the CSFB call is based on the extracted identifier;
When the processing of the call connection request message is unsuccessful, a non-CSFB call determines call connection reprocessing through a circuit switched network according to the determination result, but the called mobile communication terminal device is in a call by SRVCC handover. The CSFB call according to the step of determining the call termination
How to determine call handling. delete ◈ Claim 3 was abandoned when payment of the set registration fee was made.◈ Identifier included in the call connection request message-The identifier indicating a CSFB (Circuit Switched Fallback) call when the called mobile communication terminal device of the call connection request message is in a call by SRVCC (Single Radio Voice Call Continuity) handover is Included in the call connection request message-extracting unit for extracting,
A discrimination unit for determining whether the CSFB call is based on the extracted identifier;
When the processing of the call connection request message is unsuccessful, a non-CSFB call determines call connection reprocessing through a circuit switched network according to the determination result, but the called mobile communication terminal device is in a call by SRVCC handover. The CSFB call according to includes a decision unit for determining the termination of the call
Call processing decision device. delete ◈ Claim 5 was abandoned when payment of the set registration fee was made.◈ A circuit network switching node that transmits a call connection request message including an identifier indicating a Circuit Switched Fallback (CSFB) call when the called mobile communication terminal device is in a call by SRVCC (Single Radio Voice Call Continuity) handover;
Based on the identifier included in the call connection request message received from the circuit network switching node, it is determined whether it is a CSFB call, and when the call processing fails for the call connection request message, a non-CSFB call according to the result of the determination. Reprocesses the call connection through the circuit switched network, but the CSFB call as the called mobile communication terminal device is busy by SRVCC handover includes an IMS switching node that determines call termination.
Call processing system.

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