JP2019220898A - Radio communication terminal, communication method, and communication program - Google Patents

Abstract

To make it possible to prevent a delay in retrying an emergency call.SOLUTION: A radio communication terminal 100 comprises: a call management unit 132 that starts emergency call origination processing in response to an emergency call origination operation and manages the state of the call as being originated; a SIP processing unit 133 that starts registration processing to a SIP server in response to the start of the emergency call origination processing; and a connection control unit 134 that establishes a PDN connection for an emergency call in response to the start of the registration processing. When communication with a communication network is broken down before completion of the registration processing, the connection control unit 134 releases the PDN connection for an emergency call and notifies the call management unit 132 of the state of the PDN connection for an emergency call. After the start of the emergency call origination processing, the call management unit 132 determines a failure of the emergency call origination processing on the basis of the notification from the connection control unit 134.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a wireless communication terminal, a communication method, and a communication program.

  Conventionally, wireless communication terminals having a VoIP (Voice over IP) function using a SIP (Session Initiation Protocol) have been widely used. When the wireless communication terminal is connected to a communication network after the power is turned on, it establishes an IP packet communication path called a PDN (Packet Data Network) connection for a normal call (for example, see Patent Document 1).

  Further, the radio communication terminal establishes a PDN connection for an emergency call separately from a PDN connection for a normal call, triggered by an operation of originating an emergency call by a user. Specifically, when the call management unit of the wireless communication terminal starts the emergency call sending process in response to the emergency call sending operation, the SIP processing unit of the wireless communication terminal starts the registration process with the SIP server and performs the wireless communication. The connection control unit of the terminal establishes a PDN connection for an emergency call.

JP 2017-34470 A

  However, if the communication with the communication network is interrupted during the registration process with the SIP server after the establishment of the emergency call PDN connection, the SIP processing unit determines that the registration process has failed, and The connection control unit may request the connection control unit to release the PDN connection, and the connection control unit may release the PDN connection.

  Here, the SIP processing unit does not have a function of notifying the call management unit about the release of the emergency call PDN connection. Therefore, even though the emergency call PDN connection has been released, the call management unit continues to recognize the state of the call as the outgoing state. As a result, the display indicating that the wireless communication terminal is making a call is maintained.

  In such a case, after the user performs the call termination operation and shifts to the call termination state, the emergency call transmission process is not restarted unless the user performs the emergency call transmission operation again, so the retry of the emergency call is delayed. There's a problem.

  Therefore, an object of the present invention is to provide a wireless communication terminal, a communication method, and a communication program that can suppress a delay in retrying an emergency call.

  A wireless communication terminal according to a first feature is a wireless communication terminal that communicates with a wireless communication network and establishes a PDN connection for a normal call before sending a normal call. A call management unit that manages a call state as an outgoing call state, and a SIP processing unit that performs call processing via a SIP server in response to the outgoing call and requests establishment of a PDN connection for the emergency call. And a connection control unit for establishing a PDN connection for an emergency call in response to the request. The connection control unit releases the emergency call PDN connection when communication with the wireless communication network is interrupted, and notifies the call management unit of the state of the emergency call PDN connection. The call management unit makes a transition from the outgoing call state to the end state based on the notification.

  A communication method according to a second feature is a communication method in a wireless communication terminal that performs communication with a wireless communication network and establishes a PDN connection for a normal call before sending a normal call. Managing a call state as a calling state in accordance with the call, performing call processing via a SIP server in response to the emergency call, and establishing a PDN connection for the emergency call; Releasing the PDN connection for the emergency call when the communication with the communication network is interrupted, and transiting from the outgoing call state to the call end state.

  A communication program according to a third feature causes a wireless communication terminal to execute a communication method according to the second feature.

  A wireless communication terminal according to a fourth aspect is a wireless communication terminal that performs communication with a wireless communication network, and includes a display unit, and a display unit that sets a call state to a calling state according to an emergency call originating operation. A call management unit to be displayed; a SIP processing unit that performs call processing via a SIP server in response to the outgoing call of the emergency call and requests establishment of a PDN connection for the emergency call; And a connection control unit for establishing a PDN connection. The connection control unit releases the emergency call PDN connection when communication with the wireless communication network is interrupted, and notifies the call management unit of the state of the emergency call PDN connection. The call management unit ends the display of the transmitting state on the display unit based on the notification.

  According to the present invention, it is possible to provide a wireless communication terminal, a communication method, and a communication program capable of suppressing a delay in retrying an emergency call.

FIG. 1 is a diagram illustrating an example of an overall system configuration according to an embodiment. It is a figure which shows the problem at the time of an emergency call transmission. FIG. 2 is a diagram illustrating a configuration of a wireless communication terminal according to the embodiment. FIG. 5 is a diagram illustrating an operation of the wireless communication terminal according to the embodiment. It is a figure which shows an example of the failure determination processing of the emergency call transmission based on embodiment. It is a figure showing operation of a radio communication terminal concerning a modification of an embodiment.

  An embodiment of a communication terminal according to the present invention will be described with reference to the drawings. The communication terminal according to the present embodiment is a wireless communication terminal that performs wireless communication. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(Overall system configuration)
FIG. 1 is a diagram illustrating an example of an overall system configuration according to the present embodiment. As illustrated in FIG. 1, the system according to the present embodiment includes a wireless communication terminal 100, a plurality of wireless communication networks 200, a core network 300, an IMS (IP Multimedia Subsystem) 400, and an emergency notification receiving organization 500. Prepare. The plurality of wireless communication networks 200 include an LTE (Long Term Evolution) network 200A, a W-CDMA (Wideband-Code Division Multiple Access) network 200B, a WLAN (Wireless Local Area Network) 200C, and a WLAN (Wireless Local Area Network) 200C.

  The wireless communication terminal 100 is a communication terminal having a VoIP function using SIP. In addition, the wireless communication terminal 100 supports a plurality of wireless communication schemes such as LTE, W-CDMA, and WLAN. The wireless communication terminal 100 performs wireless communication by connecting to any one of the plurality of wireless communication networks 200. The wireless communication terminal 100 may be a smartphone, a feature phone, a tablet terminal, a wireless communication module, or a wireless communication card. The wireless communication module or the wireless communication card may be mounted on any device, but is mounted on, for example, the vehicle 10 or a notebook PC.

  LTE network 200A includes base station 210A, W-CDMA network 200B includes base station 210B, and WLAN 200C includes access point 210C. Note that the LTE network 200A may be referred to as E-UTRAN. W-CDMA network 200B may be referred to as UTRAN. However, the type of the wireless communication network is not limited to these, and for example, a GSM (registered trademark) network may be used.

  The core network 300 accommodates a plurality of wireless communication networks 200. The core network 300 includes a P-GW (Packet Data Network Gateway) 310 and an S-GW (Serving Gateway) 320. The P-GW 310 functions as an interface with the IMS 400 and an external network such as the Internet. The S-GW 320 controls data transfer between the P-GW 310 and a cellular network (LTE network 200A, W-CDMA network 200B). Note that the WLAN 200C transmits and receives data to and from the P-GW 310 without passing through the S-GW 320.

  The IMS 400 is an all-IP-based communication control system, and provides multimedia services including telephone calls using VoIP and transmission and reception of audio and video. The IMS 400 includes a SIP server 410 that performs session control by SIP. The SIP server 410 may be referred to as a CSCF (Call Session Control Function). Note that SIP is a protocol for generating, changing, and disconnecting a session necessary for exchanging voice, video, and text messages in the application layer.

  The emergency call receiving organization 500 is an organization that receives an emergency call using the emergency call telephone number transmitted from the caller and takes measures corresponding to the emergency call. For example, the emergency call receiving agency 500 may be a police station, the Japan Coast Guard, or a fire department.

  In such a system, when the wireless communication terminal 100 is first connected to any wireless communication network after power-on, an IP packet communication path called a PDN connection is established for a normal call before sending a normal call. The PDN connection may be established between the wireless communication terminal 100 and the P-GW 310 (or the IMS 400). Before transmitting a normal call, the wireless communication terminal 100 transmits a SIP registration message (REGISTER) including its own information and location information to the SIP server 410.

  The wireless communication terminal 100 performs a PDN connection for a normal call triggered by an operation of originating an emergency call by a user or an automatic operation due to an emergency such as an accident when the wireless communication terminal 100 is mounted on the vehicle 10 as a communication module. Separately, a PDN connection for an emergency call is established. The wireless communication terminal 100 exchanges a SIP message with the SIP server 410 via the emergency call PDN connection and establishes a voice session with the emergency call receiving organization 500, thereby enabling the user to make an emergency call to the emergency call receiving organization 500. A report can be made. Here, after establishing the emergency call PDN connection immediately after the emergency call, wireless communication terminal 100 transmits a SIP registration message (REGISTER) to SIP server 410. In a normal call, a SIP registration message is transmitted before calling, whereas in an emergency call, a SIP registration message is transmitted after calling.

  However, a problem arises when the wireless communication with the wireless communication network is interrupted during the registration process with the SIP server after the establishment of the emergency call PDN connection. Here, such a problem will be described with a specific example. FIG. 2 is a diagram showing problems at the time of making an emergency call.

  First, as shown in FIG. 2A, the wireless communication terminal 100 is in a connected state in a cell (LTE Cell) # 1 of the LTE network 200A. In the example of FIG. 2, an example is shown in which the tracking area code (Tracking Area Code) of the cell # 1 is “0001” and the cell identifier (cell identity) of the cell # 1 is “0000001”.

  Wireless communication terminal 100 accepts an operation of originating an emergency call from a user in cell # 1 of LTE network 200A. Here, a telephone number “110” for police is illustrated. The wireless communication terminal 100 displays a screen indicating that a call is being made in response to an emergency call originating operation, establishes an emergency call PDN connection (Emergency-PDN), and establishes an emergency call PDN connection. After that, a SIP registration message (REGISTER) is transmitted to the SIP server 410. Here, the wireless communication terminal 100 includes ID information on a connection destination (a base station, a gateway, and the like) in the P-Access-Network-Info (PANI) in the registration message (REGISTER).

  Next, as shown in FIG. 2B, the wireless communication terminal 100 moves from the area of the cell # 1 to the outside of the area, and the wireless communication with the LTE network 200A (cell # 1) is interrupted. That is, the wireless communication terminal 100 is disconnected from the wireless connection and loses the wireless communication. In such a case, the radio communication terminal 100 releases the emergency call PDN connection (Emergency-PDN). However, the wireless communication terminal 100 recognizes that the call state is the outgoing call state, and maintains the screen display indicating that the call is being made. Specifically, according to the standard specification, since the call is not controlled such as ending the call when the PDN connection is released, the terminal screen is transmitting even though the PDN connection has been released and the VoIP communication path has not been established. It keeps displaying the status.

  Next, as shown in FIG. 2C, the wireless communication terminal 100 moves into the area of the cell (LTE Cell) # 2 of the LTE network 200A and restarts wireless communication. In the example of FIG. 2, an example is shown in which the tracking area code (Tracking Area Code) of the cell # 2 is “0001” and the cell identifier (cell identity) of the cell # 2 is “00000002”.

  Here, since the wireless communication terminal 100 recognizes that the call state is the outgoing call state, it does not restart the outgoing call processing even if the mobile communication terminal 100 moves into the area of the cell # 2. Continue to maintain the screen display shown. For this reason, the user recognizes that the wireless communication terminal 100 is continuing the calling process based on the screen display, and continues waiting for the establishment of the call. In such a case, the emergency call transmission process is not restarted unless the user notices the unusual situation and the user performs the call termination operation and performs the emergency call transmission operation again.

  When the user performs the call end operation and performs the emergency call originating operation again, the wireless communication terminal 100 establishes an emergency call PDN connection (Emergency-PDN) in the cell # 2, and registers the SIP registration message (REGISTER). ) To the SIP server 410. Here, the wireless communication terminal 100 includes ID information on a connection destination (a base station, a gateway, and the like) in the P-Access-Network-Info (PANI) in the registration message (REGISTER).

  As a result, although the emergency call is established, there is a problem that the retry of the emergency call is delayed. Hereinafter, the configuration and operation of the wireless communication terminal 100 that can solve such a problem will be described.

(Configuration of wireless communication terminal)
FIG. 3 is a diagram illustrating a configuration of the wireless communication terminal 100 according to the present embodiment. As shown in FIG. 3, the wireless communication terminal 100 includes an antenna 110, a front end unit 120, a control unit 130, a storage unit 141, a display unit 142, an operation unit 143, an audio output unit 144, And an input unit 145. Wireless communication terminal 100 may further include another configuration such as a power supply unit (battery). At least one of the antenna 110, the display unit 142, the operation unit 143, the audio output unit 144, and the audio input unit 145 may have an external configuration.

  The antenna 110 is used for transmitting and receiving a radio signal. The front end unit 120 performs amplification processing, filter processing, and the like on the wireless signal received by the antenna 110, converts the wireless signal into a baseband signal, and outputs the baseband signal to the control unit 130. Further, the front end unit 120 converts the baseband signal input from the control unit 130 into a radio signal, performs an amplification process or the like, and outputs the signal to the antenna 110. In the present embodiment, the front-end unit 120 includes an LTE wireless unit 121 that transmits and receives LTE wireless signals, a W-CDMA wireless unit 122 that sends and receives W-CDMA wireless signals, and a WLAN wireless unit 123 that sends and receives WLAN wireless signals. Is provided.

  The control unit 130 includes a DSP, a CPU, a codec, and the like, and performs various processes and controls in the wireless communication terminal 100. The storage unit 141 includes a volatile memory and a nonvolatile memory, and stores a program executed by the control unit 130 and information used for processing by the control unit 130. The display unit 142 includes a display, and displays an image based on an image signal input from the control unit 130. The operation unit 143 includes various buttons and the like, receives an operation input from a user, and outputs an operation signal indicating the operation content to the control unit 130. At least a part of the operation unit 143 may be integrated with the display unit 142 as a touch panel. The audio output unit 144 includes a speaker, and outputs audio based on an audio signal input from the control unit 130. The voice input unit 145 includes a microphone, receives a voice input from a user, and outputs a voice signal to the control unit 130.

  The control unit 130 includes a telephone application processing unit 131, a call management unit 132, a SIP processing unit 133, and a connection control unit 134. Note that the telephone application processing unit 131 may be a part of an operating system (OS).

  The telephone application processing unit 131 executes a telephone application and provides a telephone function to the user. The telephone application processing unit 131 displays a telephone number input screen on the display unit 142, and when a telephone number is input by the user using the operation unit 143 and a call operation is performed, the telephone application processing unit 131 requests the call management unit 132 to perform a call transmission process. I do. In addition, the telephone application processing unit 131 causes the display unit 142 to display a calling screen.

  The telephone application processing unit 131 determines whether or not an emergency call originating operation has been performed based on the input telephone number. For example, when a specific telephone number for the police, the Japan Coast Guard, or the fire department is input, the telephone application processing unit 131 determines that an emergency call originating operation has been performed, and performs an emergency call originating process on the call management unit. 132.

  Upon receiving the notification that the call has been established from the call management unit 132, the telephone application processing unit 131 switches to the busy screen. The telephone application processing unit 131 switches to the end screen when receiving a notification (end-of-call notification) that the calling process or the call has ended from the call management unit 132 or when the user performs an end operation.

  The call management unit 132 is controlled by the telephone application processing unit 131 and manages the state of a call. When the call application process is requested by the telephone application processing unit 131 to start the call originating process, the call managing unit 132 starts the call originating process, and manages the state of the call as the calling state. When the telephone application processing unit 131 requests the start of the emergency call transmission processing, the call management unit 132 starts the emergency call transmission processing and notifies the SIP processing unit 133 of the emergency call transmission request.

  The SIP processing unit 133 is controlled by the call management unit 132, and sends and receives signaling according to the SIP to and from the SIP server 410. The SIP processing unit 133 may be a part of the IMS function unit for using the IMS 400. The SIP processing unit 133 starts registration processing (SIP Registration) with the SIP server 410 in response to the start of the emergency call transmission processing, and requests the connection control unit 134 to establish a PDN connection for an emergency call.

  After the registration processing with the SIP server 410 is completed, the SIP processing unit 133 transmits a call (voice session) with the emergency report receiving organization 500 by transmitting an outgoing message (INVITE message) to the emergency report receiving organization 500. Establish. When the call is established, the SIP processing unit 133 notifies the call management unit 132 of the fact, and the call management unit 132 changes the call state to the busy state.

  On the other hand, when it is determined that the registration processing (SIP Registration) with the SIP server 410 has failed, the SIP processing unit 133 requests the connection control unit 134 to release the PDN connection for the emergency call. For example, after transmitting a registration message (REGISTER) to the SIP server 410, if the SIP processing unit 133 times out without receiving a response message (200 (OK)) corresponding to the registration message, the SIP processing unit 133 It is determined that registration processing (SIP Registration) to the server has failed.

  The connection control unit 134 is controlled by the SIP processing unit 133 and establishes and releases a PDN connection. The connection control unit 134 establishes a PDN connection for an emergency call in response to the start of the registration processing (SIP Registration). The connection control unit 134 releases the emergency call PDN connection when communication with the currently connected communication network is interrupted before the completion of the registration processing. Specifically, when the connection processing unit 134 determines that the SIP processing unit 133 has failed in the registration processing (SIP Registration) with the SIP server 410, the connection control unit 134 responds to the request from the SIP processing unit 133 for an emergency call. Release the PDN connection.

  The connection control unit 134 notifies the call management unit 132 of the status of the emergency call PDN connection. The connection control unit 134 may notify the call management unit 132 via the SIP processing unit 133 or may directly notify the call management unit 132 without via the SIP processing unit 133. The connection control unit 134 notifies the call management unit 132 of a change in the state of the emergency call PDN connection when the state of the emergency call PDN connection is changed. Alternatively, the connection control unit 134 may notify the call management unit 132 of the current state of the emergency call PDN connection at a predetermined cycle.

  After the start of the emergency call transmission process, the call management unit 132 determines the failure of the emergency call transmission process based on the notification from the connection control unit 134. Specifically, the call management unit 132 manages the state of the call as an outgoing call state, and when receiving from the connection control unit 134 a notification indicating the release of the PDN connection for an emergency call, It is determined that the transmission processing has failed.

  The call management unit 132 manages the state of the call as the outgoing state, receives from the connection control unit 134 a notification indicating the release of the PDN connection for an emergency call, and performs other communication available other than the communication network. If no network exists, it may be determined that the emergency call originating process has failed. That is, the call management unit 132 manages the state of the call as the outgoing call state, and even if a notification indicating the release of the PDN connection for an emergency call is received from the connection control unit 134, the available If such a communication network exists, the emergency call originating process may be continued using the other communication network.

  In the present embodiment, when the call management unit 132 determines that the emergency call transmission processing has failed, the call management unit 132 ends the emergency call transmission processing, and changes the state of the managed call from the outgoing call state to the call end state. . In addition, the call management unit 132 notifies the upper level (the telephone application processing unit 131) of the end of the call. The telephone application processing unit 131 receives the notification of the end state, indicates the end state on the screen, and notifies the user.

(Operation of wireless communication terminal)
FIG. 4 is a diagram illustrating an operation of the wireless communication terminal 100 according to the present embodiment.

  As shown in FIG. 4, when the user operates the emergency call transmission, the telephone application processing unit 131 notifies the call management unit 132 of a transmission request (step S1), and the call management unit 132 transmits the transmission request to the SIP processing unit 133. Notify (step S2).

  The call management unit 132 and the telephone application processing unit 131 enter a calling state (step S3).

  The SIP processing unit 133 requests the connection control unit 134 to establish a PDN connection for an emergency call in order to secure a SIP REGISTER transmission path (step S4).

  When receiving the connection request for the emergency call PDN connection from the SIP processing unit 133, the connection control unit 134 establishes the emergency call PDN connection (step S5). The connection control unit 134 notifies the call management unit 132 and the SIP processing unit 133 that the PDN connection for the emergency call has been established (step S6). At this time, the call management unit 132 sets the state of the PDN connection to “connected” (established).

  After the emergency call PDN connection is established, the SIP processing unit 133 transmits a SIP REGISTER (step S7).

  The SIP processing unit 133 expects to receive 200 (OK), which is an acknowledgment of REGISTER transmission, but cannot receive 200 (OK) due to the loss of the communication network (interruption of wireless communication) (step S8). As a result, the timer that defines the time to wait for reception of 200 (OK) times out (step S9), and the SIP processing unit 133 determines that the registration processing has failed.

  The SIP processing unit 133 requests the connection control unit 134 to release the emergency call PDN connection in response to the timeout of 200 (OK) (step S10). Here, the SIP processing unit 133 does not notify the call management unit 132 of the failure of the emergency call transmission with the release of the emergency call PDN connection.

  The connection control unit 134 releases the emergency call PDN connection in response to the request from the SIP processing unit 133 (step S11). The connection control unit 134 notifies the call management unit 132 that the PDN connection for the emergency call has been released (step S12).

  The call management unit 132 determines the failure of the emergency call originating process based on the notification from the connection control unit 134 (Step S13). The details of the determination process will be described later.

  When determining that the emergency call transmission process has failed, the call management unit 132 ends the emergency call transmission process, and changes the state of the managed call from the outgoing call state to the call end state (step S14). As a result, the telephone application processing section 131 switches the display on the display section 142 from the calling screen to the end screen.

  FIG. 5 is a diagram illustrating an example of the emergency call transmission failure determination process (step S13 in FIG. 4). As described above, when the connection state of the PDN is changed, the connection control unit 134 notifies the call management unit 132 of the state change.

  As shown in FIG. 5, upon receiving the notification from the connection control unit 134, the call management unit 132 checks whether the received notification content satisfies the following conditions. The order in which the conditions are determined is not limited to the order shown in FIG.

  -Whether or not the state is related to a PDN connection for an emergency call (step S131). For example, the notification from the connection control unit 134 includes information indicating the type of the target PDN connection. The call management unit 132 confirms, based on the information, whether or not the state change is related to the emergency call PDN connection.

  -Whether or not the state before the PDN is "connected" (step S132). Since the connection control unit 134 notifies each time the state of the PDN connection changes, the call management unit 132 changes the state of the PDN connection to “connected” (established) based on the notification previously received from the connection control unit 134. Check if it is.

  -Whether or not the current state of the PDN is "release / disconnection" (step S132). The call management unit 132 checks whether the state of the PDN connection is “release / disconnection” based on the notification received this time from the connection control unit 134.

  -Whether a VoIP emergency call exists (step S134). Since the call management unit 132 manages (stores) that the VoIP emergency call is in a state of being outgoing, it checks whether or not there is a VoIP emergency call based on the managed state.

  -Whether there is a usable communication network other than the currently used communication network (step S135). The call management unit 132 acquires, for example, the reception signal state of each wireless communication network 200 from the front end unit 120. The call management unit 132, based on the reception signal state of each wireless communication network 200, uses a wireless communication network (for example, the W-CDMA network 200B, the WLAN 200C, etc.) other than the currently used communication network (for example, the LTE network 200A). Check if) exists.

  The call management unit 132 is a state change related to the PDN connection for an emergency call, the state before the PDN is “connected”, the current state of the PDN is “released / disconnected”, and there is a VoIP emergency call. However, if there is no available communication network other than the currently used communication network, it is determined that the emergency call transmission processing has failed, the emergency call transmission processing is terminated, and the state of the managed call is being transmitted. A transition is made from the state to the end state (step S136). In addition, the call management unit 132 notifies the upper level (the telephone application processing unit 131) of the end of the call. Otherwise, the call management unit 132 continues the emergency call originating process (step S133).

(Summary of Embodiment)
The radio communication terminal 100 according to the present embodiment starts an emergency call originating process in response to an emergency call originating operation, and a call management unit 132 that manages the state of the call as an outgoing call state. In accordance with the start of the registration process, there are provided a SIP processing unit 133 for starting a registration process to the SIP server and a connection control unit 134 for establishing a PDN connection for an emergency call. The connection control unit 134 releases the emergency call PDN connection when the communication with the communication network is interrupted before the completion of the registration processing, and notifies the call management unit 132 of the state of the emergency call PDN connection. After the start of the emergency call transmission process, the call management unit 132 determines the failure of the emergency call transmission process based on the notification from the connection control unit 134. Thereby, the call management unit 132 can appropriately grasp that the emergency call PDN connection has been released.

  In the present embodiment, when it is determined that the emergency call transmission processing has failed, the call management unit 132 ends the emergency call transmission processing, and makes a transition from the transmitting state to the call termination state. Thus, the display indicating that the communication terminal is making a call can be ended, so that the user can recognize that the emergency call transmission has failed. Therefore, the emergency call transmission process can be restarted by the user performing the emergency call transmission operation again.

  In the present embodiment, when the state of the emergency call PDN connection is changed, the connection control unit 134 notifies the call management unit 132 of the change in the state of the emergency call PDN connection. The call management unit 132 manages the state of the call as the outgoing call state, and when the notification indicating the release of the PDN connection for the emergency call is received from the connection control unit 134, the emergency call transmission processing has failed. Is determined. As a result, immediately after the emergency call PDN connection is released, the call management unit 132 can determine that the emergency call originating process has failed.

  In the present embodiment, the call management unit 132 manages the state of the call as the outgoing state, receives from the connection control unit 134 a notification indicating the release of the emergency call PDN connection, and performs the communication currently being used. If there is no other communication network available other than the network, it is determined that the emergency call originating process has failed. That is, the call management unit 132 manages the state of the call as the outgoing call state, and even if a notification indicating the release of the PDN connection for an emergency call is received from the connection control unit 134, the available If such a communication network exists, the emergency call originating process can be continued using the other communication network.

  The wireless communication terminal 100 may display a message indicating that a call is in progress when the emergency call is successful and the call is in progress (in communication). Basically, even if the communication is interrupted and the PDN is released, the display indicating that a call is in progress remains. The wireless communication terminal 100, apart from the state of the PDN, goes out of the service area, and the voice data is in a non-communication state. Therefore, the monitoring timer is activated. May be stopped. Further, when the communication is interrupted and the PDN is released, the display during the call may be stopped.

(Another embodiment)
In the above-described embodiment, when the call management unit 132 determines that the emergency call transmission processing has failed, the call management unit 132 ends the emergency call transmission processing, and changes the state of the managed call from the outgoing call state to the call termination state. An example of the operation has been described.

  However, if the call management unit 132 determines that the emergency call transmission processing has failed, the call management unit 132 maintains the outgoing call state until the communication with the communication network or the other communication network used by the emergency call transmission processing is restarted. Emergency call transmission may be automatically restarted in response to the restart.

  FIG. 6 is a diagram illustrating an operation of the wireless communication terminal 100 according to the modification of the embodiment. As shown in FIG. 6, operations in steps S1 to S13 are the same as the operations according to the above-described embodiment (see FIG. 4).

  When it is determined that the emergency call transmission process has failed (step S13), the call management unit 132 maintains the outgoing call state (step S21). The call management unit 132 waits until communication with the communication network used by the call management unit or another communication network is resumed.

  In step S22, the communication is restarted (for example, the wireless communication terminal 100 enters the area of another cell), and the call management unit 132 detects that the communication is restarted.

  When detecting that the communication has been resumed, the call management unit 132 notifies the SIP processing unit 133 of a call request (step S23).

  The SIP processing unit 133 requests the connection control unit 134 to establish a PDN connection for an emergency call in order to secure a SIP REGISTER transmission path (step S24).

  When receiving the connection request for the emergency call PDN connection from the SIP processing unit 133, the connection control unit 134 establishes the emergency call PDN connection (step S25). The subsequent operation is the same as in the above-described embodiment.

  Note that an upper limit may be set for the waiting time in step S21. That is, when it is determined that the emergency call transmission process has failed (step S13), the call management unit 132 waits for the communication to be resumed for a fixed time. The processing may be ended and the state may be shifted to the end state.

(Other embodiments)
In the embodiment described above, an example in which the communication terminal is the wireless communication terminal 100 has been described. However, a communication terminal that performs wired communication (for example, a stationary VoIP terminal) may be used as the communication terminal according to the present invention.

  Note that a program that causes a computer to execute each process performed by the wireless communication terminal 100 may be provided. The program may be recorded on a computer-readable medium. With a computer-readable medium, it is possible to install a program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. In addition, a circuit that executes each process performed by the wireless communication terminal 100 may be integrated, and a semiconductor integrated circuit (chip set, SoC) mounted on the wireless communication terminal 100 may be configured.

  As described above, the present embodiment has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist. .

10: Vehicle 100: Wireless communication terminal 110: Antenna 120: Front end unit 121: LTE wireless unit 122: W-CDMA wireless unit 123: WLAN wireless unit 130: Control unit 131: Telephone application processing unit 132: Call management unit 133: SIP processing unit 134: Connection control unit 141: Storage unit 142: Display unit 143: Operation unit 144: Audio output unit 145: Audio input unit 200: Wireless communication network 200A: LTE network 200B: W-CDMA network 200C: WLAN
210A: base station 210B: base station 210C: access point 300: core network 410: SIP server 500: emergency call receiving organization

Claims (8)

A wireless communication terminal that communicates with a wireless communication network and establishes a normal call PDN connection before sending a normal call,
A call management unit that manages the state of the call as an outgoing call state in response to the outgoing emergency call;
A SIP processing unit that performs call processing via a SIP server in response to the outgoing emergency call and requests establishment of a PDN connection for an emergency call;
A connection control unit for establishing a PDN connection for an emergency call in response to the request,
The connection control unit releases the emergency call PDN connection when communication with the wireless communication network is interrupted, and notifies the call management unit of the state of the emergency call PDN connection,
The wireless communication terminal, wherein the call management unit makes a transition from the outgoing call state to a call end state based on the notification. After the PDN connection for the emergency call is established, the SIP processing unit registers information of a wireless communication network (PANI: P-Access-Network-Info) in the SIP server,
The wireless communication terminal according to claim 1, wherein the connection control unit releases the emergency call PDN connection when the registration is not successful, and notifies the call management unit of the state of the emergency call PDN connection. .   Upon receiving the notification, the call management unit maintains the outgoing call state until communication with the wireless communication network or another wireless communication network is restarted, and issues an emergency call in response to the restart of the communication. The wireless communication terminal according to claim 1, which restarts. The connection control unit, when the state of the emergency call PDN connection is changed, notifies the call management unit of the state change of the emergency call PDN connection,
The call management unit manages the state of the call as the outgoing call state, and, when receiving a notification indicating the release of the PDN connection for the emergency call from the connection control unit, changes the call state from the outgoing call state. The wireless communication terminal according to any one of claims 1 to 3, wherein the wireless communication terminal changes to a call end state.   The call management unit manages a call state as the outgoing state, receives a notification indicating release of the PDN connection for the emergency call from the connection control unit, and can be used for other than the wireless communication network. The wireless communication terminal according to claim 4, wherein when there is no other wireless communication network, the state is changed from the outgoing call state to the end state. A communication method in a wireless communication terminal that performs communication with a wireless communication network and establishes a PDN connection for a normal call before sending a normal call,
Managing the state of the call as an outgoing state in response to the outgoing emergency call;
Performing call processing via a SIP server in response to the outgoing emergency call, and establishing a PDN connection for the emergency call;
Releasing the PDN connection for the emergency call when the communication with the wireless communication network is interrupted, and transitioning from the outgoing call state to the call end state.   A communication program for causing a wireless communication terminal to execute the communication method according to claim 6. A wireless communication terminal that communicates with a wireless communication network,
A display unit,
A call management unit that displays the state of the call on the display unit as an outgoing state in response to the outgoing emergency call,
A SIP processing unit that performs call processing via a SIP server in response to the outgoing call of the emergency call, and requests establishment of a PDN connection for the emergency call;
A connection control unit for establishing a PDN connection for an emergency call in response to the request,
The connection control unit releases the emergency call PDN connection when communication with the wireless communication network is interrupted, and notifies the call management unit of the state of the emergency call PDN connection,
The wireless communication terminal, wherein the call management unit terminates the display of the transmitting state on the display unit based on the notification.

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