Communication system, communication terminal, communication method, and non-transitory computer-readable medium

The present disclosure relates to a communication system, a communication terminal, a communication method, and a non-transitory computer-readable medium.

There is known a group call technology that enables communication between multiple users belonging to a specific group by enabling voice transmission and reception between the communication terminals of the users. A group call is started when a calling terminal transmits a request to start a group call to other terminals in the group, and the other terminals respond to the request. However, if the terminal to which the call request is sent is outside the communication range, the terminal cannot participate in the group call. It is desirable to allow such a terminal to join an already started group call midway when returning to the communication range from outside the communication range.

As a related technique, for example, Patent Document 1 discloses a group call system that allows a mobile communication terminal that did not participate in a group call to participate in the group call later. The system disclosed in Patent Document 1 includes a plurality of mobile communication terminals and a group call control server that provides a function of a group call between the plurality of mobile communication terminals. When a midway joining terminal that does not respond to a participation request from a calling terminal and joins the group call midway receives a group call participation request signal from the group call control server, it registers the call history information from the calling terminal in an incoming call history table. When the user selects the call history information registered at the time of no response and presses a group call start request button, the midway joining terminal transmits a midway joining request signal including a group ID to the group call control server. The group call control server performs a predetermined process and allows the midway joining terminal to join the group corresponding to the received group ID.

As another related technique, Patent Document 2 discloses a communication system that allows a mobile station that was out of range of a network and therefore could not answer a call (an unanswered mobile station) to join a group call midway. The communication system disclosed in Patent Document 2 includes a base station, a group call server, and an SMS server. The group call server receives an INVITE (mid-call join) message for allowing the unanswered mobile station to join a group call midway from the calling mobile station, and holds the message until the unanswered mobile station moves into range and performs registration processing. When the unanswered mobile station performs registration processing, the group call server transmits the held INVITE (mid-call join) to the unanswered mobile station. The unanswered mobile station transmits 180 Ringing and 200 OK to the calling mobile station via the group call server. When an ACK is transmitted from the calling mobile station to the group call server, the mid-call participation of the unanswered mobile station in the group call is completed.

<p><patcit num="1"><text>JP 2008-067083 A</text></patcit><patcit num="2"><text>JP 2008-005169 A</text></patcit></p>

<p>For example, while a communication terminal is outside the communication range, requests to join multiple group communications may be made. In such a case, after the communication terminal moves from outside the communication range to within the communication range, it receives call history information related to multiple group communications. The user checks the multiple call history information displayed on the communication terminal and considers which group communication to join mid-way. The communication terminal accepts the user's selection of the group communication to join mid-way and makes a mid-way join request to a server that controls the group communications. In particular, when there are a large number of call histories, the user will have to take the time to check and select from multiple call history information. Patent Documents 1 and 2 do not take such problems into consideration.</p><p>In view of the above-mentioned problems, an object of the present disclosure is to provide a communication system, a communication terminal, a communication method, and a non-transitory computer-readable medium that enable easy selection of a group communication to join mid-stream.</p>

<p>A communication system according to the present disclosure includes a communication terminal and a server that controls group communication among a plurality of the communication terminals, the communication terminal having an acquisition means for acquiring information regarding a group communication that has already been started among the plurality of communication terminals and is in an unresponsive state because it did not respond at the start, a selection means for selecting one of the group communications from at least one of the group communications that is a candidate for participation based on the acquired information, and a transmission means for transmitting a participation request for the selected group communication to the server, and the server having a participation acceptance means for accepting the participation of the communication terminal in the selected group communication.</p><p>A communication terminal according to the present disclosure includes an acquisition means for acquiring information regarding a group communication that has already been started between a plurality of communication terminals and is in an unresponsive state due to failure to respond at the start of the group communication, a selection means for selecting one of the group communications from at least one of the group communications that is a candidate for participation based on the acquired information, and a transmission means for transmitting a request to participate in the selected group communication to a server that controls the group communication between the plurality of communication terminals.</p><p>The communication method disclosed herein acquires information regarding a group communication that has already been started between a plurality of communication terminals but is in an unresponsive state because it did not respond at the time of initiation, selects one of at least one of the group communications that is a candidate for joining based on the acquired information, and sends a request to join the selected group communication to a server that controls the group communication between the plurality of communication terminals.</p><p>A non-transitory computer-readable medium storing a communication program according to the present disclosure causes a computer to execute an acquisition process for acquiring information regarding a group communication that has already been started between a plurality of communication terminals and is in an unresponsive state due to failure to respond at the start of the group communication, a selection process for selecting one of the group communications from at least one of the group communications that is a candidate for joining based on the acquired information, and a transmission process for sending a request to join the selected group communication to a server that controls the group communication between the plurality of communication terminals.</p>

<p>The present disclosure makes it possible to provide a communication system, a communication terminal, a communication method, and a non-transitory computer-readable medium that allow a user to easily select a group communication to join mid-session.</p>

<figref num="1">1 is a block diagram showing a configuration of a communication system according to a first embodiment.</figref><figref num="2">FIG. 11 is a diagram illustrating an overview of a communication system according to a second embodiment.</figref><figref num="3">FIG. 11 is a block diagram showing a configuration of a communication terminal according to a second embodiment. </figref><figref num="4">FIG. 11 is a diagram showing a display screen of a communication terminal according to the second embodiment. </figref><figref num="5">FIG. 11 is a block diagram showing a configuration of a server according to the second embodiment.</figref><figref num="6">FIG. 11 is a sequence diagram showing a process when a communication terminal returns to within range from outside range in the second embodiment.</figref><figref num="7">FIG. 11 is a sequence diagram showing a process when a communication terminal ends another communication in the second embodiment. </figref><figref num="8">FIG. 11 is a diagram illustrating an example of a hardware configuration of a communication terminal or the like according to a second embodiment.</figref>

&lt;First embodiment&gt; Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a block diagram showing a configuration of a communication system 1 according to this embodiment. The communication system 1 includes a communication terminal 10 and a server 20 that controls group communication between a plurality of communication terminals 10.

The communication terminal 10 includes an acquisition unit 11, a selection unit 12, and a transmission unit 13. The acquisition unit 11 acquires information about group communications that have already been started among a plurality of communication terminals 10 and that are in an unresponsive state due to failure to respond at the start of the group communications. The selection unit 12 selects one of at least one group communications that is a candidate for participation, based on the information acquired by the acquisition unit 11. The transmission unit 13 transmits a participation request to the server 20 for the selected group communication. The server 20 includes a participation acceptance unit 21. The participation acceptance unit 21 accepts participation of the communication terminal 10 in the selected group communication.

In the communication system 1 according to the present embodiment, the acquisition unit 11 of the communication terminal 10 acquires information about a group communication that has already started but is in an unresponsive state because the communication terminal 10 did not respond at the start. The selection unit 12 of the communication terminal 10 selects one of the group communications from at least one group communication that is a candidate for the communication terminal 10 to participate in, based on the acquired information. The transmission unit 13 of the communication terminal 10 transmits a participation request to the selected group communication to the server 20. In response to this, the participation acceptance unit 21 of the server 20 accepts the participation of the communication terminal 10 in the selected group communication. In this way, in the communication system 1 according to the present embodiment, the communication terminal 10 selects one of the group communications from at least one group communication that is a candidate for the communication terminal 10 to participate in, based on information about the group communication that is in an unresponsive state. Therefore, according to the communication system 1 according to the present embodiment, it is easy to select a group communication to participate in mid-way.

&lt;Embodiment 2&gt; Next, an overview of a communication system 1000 according to embodiment 2 will be described with reference to Fig. 2. Embodiment 2 is a specific example of the above-mentioned embodiment 1. Fig. 2 is a diagram showing an overview of the communication system 1000 according to this embodiment.

The communication system 1000 includes a plurality of communication terminals 100a to 100e, a server 200, and a base station 300. The number of base stations 300 included in the communication system 1000 is not limited to one. Furthermore, the number of communication terminals 100 included in the communication system 1000 is not limited to five. The communication terminals 100a to 100e and the base station 300 are connected to the server 200 via a network N. The network N is a wired or wireless communication line. The network N may be, for example, the Internet, a Long Term Evolution (LTE) network, a 5th Generation (5G) network, or the like.

The communication terminals 100a to 100e are communication terminals capable of using a group communication function provided by the server 200. For example, by installing a specific application, the communication terminals 100a to 100e can perform group communication provided by the server 200 via the application. The communication terminals 100a to 100e may be communication terminals such as mobile phones, smartphones, tablet terminals, PHS, or landlines. In the following description, the communication terminals 100a to 100e may be simply referred to as communication terminals 100. Furthermore, the above-mentioned base station 300 is not essential when the communication terminal 100 is a landline phone, and it is sufficient that the communication terminal 100 is connected to the network N via an exchange, a repeater, or the like.

Here, it is assumed that the communication terminals 100a to 100e belong to the same group in the group communication function provided by the server 200. The communication terminals 100a to 100e can communicate with each other individually, not limited to group communication. Furthermore, the communication terminals 100a to 100e may further belong to different groups.

The server 200 provides a function of group communication between a plurality of communication terminals 100, and controls the group communication between the communication terminals 100. The group communication provided by the server 200 may include, for example, a group call, a web conference, and a chat function between the communication terminals 100a to 100e. In these group communications, communication data transmitted and received between the communication terminals 100 may include voice data, image data, video data, text data, and the like.

In this embodiment, an example will be described in which the server 200 controls a group call among the communication terminals 100a to 100e. The server 200 is configured, for example, with a Session Initiation Protocol (SIP) server, and executes SIP sequence processing when communicating between the communication terminals 100. However, the present invention is not limited to this, and a communication protocol other than SIP may be used for communication between the communication terminals 100.

When the server 200 receives a request to start a group call from any of the communication terminals 100 belonging to the group, the server 200 calls the communication terminals 100 belonging to the group. The server 200 issues a new session ID for identifying the group call for which the server 200 receives the request to start, and manages the group call. In the following description, the period from the start to the end of the group call may be referred to as a session.

Here, it is assumed that, among the communication terminals 100a to 100e, the communication terminal 100a makes a request to start a group call to the server 200, the communication terminals 100b to 100d respond to the request, and the communication terminal 100e does not respond to the request.

The server 200 starts a group call among the communication terminals 100a to 100d. The server 200 transmits an incoming call notification to the communication terminal 100e that did not respond to the call, indicating that there has been a request to join the group call. When the communication terminal 100e that is now able to respond transmits a join request to the server 200, the server 200 accepts this request and performs control so that the communication terminal 100e joins the already started group call midway.

For example, if communication terminal 100e is unable to respond because it is outside the communication range, when it moves within the communication range, it notifies server 200 that it has returned within the range and receives the incoming call notification. Communication terminal 100e decides to join the group call based on the contents of the incoming call notification, and transmits a mid-call join request to server 200.

Furthermore, when the communication terminal 100e is within the communication range but is unable to respond because it is engaged in other communication, it receives an incoming call notification from the server 200 while engaging in the other communication, and stores the received notification in the storage unit 190 described below. The other communication may be, for example, a call with another communication terminal, a web conference, or a chat. This may also include a case where the communication terminal 100e is running an application that restricts a call from the server 200 or communication with another communication terminal. When the other communication ends or when a state in which the other communication is restricted ends, the communication terminal 100e decides to participate in the group call based on the content of the incoming call notification, and transmits a mid-call join request to the server 200.

In addition, even if the communication terminal 100e is not turned on when the group communication starts or if the user does not notice the incoming call because the terminal is muted, the communication terminal 100e performs the same processing as when the user is unable to respond because the terminal is engaged in other communication.

Next, the configuration of the communication terminal 100 will be described. Fig. 3 is a block diagram showing the configuration of the communication terminal 100. The communication terminal 100 corresponds to the communication terminal 10 of the first embodiment. The communication terminals 100a to 100e each have the configuration of the communication terminal 100 shown in the figure. The communication terminal 100 includes an acquisition unit 110, a selection unit 120, a communication unit 130, an input/output unit 140, and a storage unit 190.

The acquisition unit 110 corresponds to the acquisition unit 11 in the embodiment 1. The acquisition unit 110 acquires information about group communication that has already been started among a plurality of communication terminals 100 and is in an unresponsive state due to a failure to respond at the start of the group communication.

The information on the group communication may be information for identifying an unanswered group communication to which communication terminal 100 was called. Acquirer 110 receives information on the unanswered group communication from server 200, associates the information with a session ID 1931 for identifying the group communication, and stores the information in storage 190 as call history information 193. Session ID 1931 corresponds to session ID 2931, which will be described later.

As shown in the figure, the call history information 193 may be associated with, for example, a session ID 1931, a target group ID 1932, a calling terminal ID 1933, and a call date and time 1934. The target group ID 1932 is identification information for identifying a target group that is a target of a session. The target group ID 1932 corresponds to a target group ID 2932 described later. The calling terminal ID 1933 is identification information for identifying a calling terminal. The calling terminal ID 1933 corresponds to a calling terminal ID 2933 described later. The call date and time 1934 is information indicating the date and time when a call was made to the communication terminal 100. Without being limited to this, the call history information 193 may include various information regarding group communication that is in an unanswered state because the communication terminal 100 did not respond at the start of the call.

Here, in a group call that has already been started among the communication terminals 100a to 100d, the communication terminal 100e that is in an unanswered state because it did not respond at the start of the group call acquires the above-mentioned information from the server 200 at the acquisition unit 110. Note that the acquisition unit 110 may acquire this information not from the server 200 but from any of the other communication terminals 100a to 100d in the group.

The acquisition unit 110 may acquire information about multiple unanswered group calls. For example, when multiple group calls are made while the communication terminal 100e is out of communication range, the acquisition unit 110 acquires information about these group calls. The acquisition unit 110 identifies the multiple group calls that were called by the session ID 1931, and stores each of them as the call history information 193.

The selection unit 120 corresponds to the selection unit 12 in the first embodiment. The selection unit 120 selects one of the group communications to join from at least one group communication that is a candidate for joining, based on the call history information 193 acquired by the acquisition unit 110. The selection unit 120 may display information about the selected group communication on the input/output unit 140 to notify the user. In this way, the user can know the group .

In addition, when multiple pieces of call history information 193 are acquired by the acquisition unit 110, the selection unit 120 selects one of the group communications to participate in from at least one group communication that is a candidate to participate in, based on the multiple pieces of call history information 193 acquired.

For example, the selection unit 120 selects one of at least one group communication that is a candidate for participation based on start date and time information of group communication included in the acquired multiple call history information 193. Here, the start date and time information of the group communication may be included in the call history information 193 acquired by the acquisition unit 110. Alternatively, the call date and time 1934 at which a call to the group communication is made may be regarded as the start date and time of the group communication. For example, the selection unit 120 may select the group communication with the earliest start date and time, or the group communication with the latest start date and time. Furthermore, the selection unit 120 may target group communications that are within a predetermined time (e.g., two hours) from the start date and time of the group communication and select from among them. Furthermore, the selection unit 120 may acquire the end date and time of the group communication from the server 200, and select the group communication by excluding the group communication that has ended.

The selection unit 120 may also determine which group communication to participate in based on the priority of the group communication. The priority of the group communication may be set by the communication terminal 100e, or may be acquired from the priority set by another communication terminal 100. When the priority is set by the communication terminal 100e, the selection unit 120 may set the priority by referring to the belonging group information 192 stored in the storage unit 190, for example. For example, when a call is made from a group having a group attribute 1922 of "business" and a group having a group attribute 1922 of "hobby", the selection unit 120 may set a higher priority for the "business" group than for the "hobby" group. In addition, the selection unit 120 may set the priority according to the caller, the number of terminals participating in the group communication, the number of calls, or the like.

In the case where the priority is set on the side of the other communication terminal 100, for example, the priority, importance, or urgency of each group communication may be set at the start of the group call and transmitted to the server 200. The acquisition unit 110 may acquire these information by including them in the call history information 193, and the selection unit 120 may determine the group communication to participate in based on this information.

In this way, the selection unit 120 can select a group communication to participate in without waiting for a user operation, depending on the start date and time information of the group communication, the priority of the group communication, etc. Therefore, for example, by setting in advance to select the group communication with the earliest start date and time, it is possible to automatically select the last incoming group communication and make a call.

The communication unit 130 communicates with other communication terminals 100 and the server 200. The communication unit 130 receives a missed call notification including information about a group communication that is in an unanswered state from the server 200. When the communication terminal 100 moves from outside the communication range and returns to the communication range, the communication unit 130 transmits to the server 200 a notice that the communication terminal 100 has returned to the communication range. In response to this, the communication unit 130 receives the missed call notification transmitted from the server 200. Also, when the communication terminal 100 is in the communication range but in an unanswered state because it was performing another communication, the communication unit 130 receives the missed call notification from the server 200 while performing the other communication.

Moreover, the communication unit 130 corresponds to the transmission unit 13 in the first embodiment. The communication unit 130 transmits to the server 200 a request to join the group communication selected by the selection unit 120. For example, it is assumed that the acquisition unit 110 acquires only one piece of call history information 193, and the selection unit 120 selects the group communication corresponding to the information. The communication unit 130 automatically transmits the request to join the group communication to the server 200. Alternatively, when the user inputs to the input/output unit 140 that he/she wishes to join the group communication, the communication unit 130 transmits the request to join the group communication to the server 200.

Also, assume that a plurality of pieces of call history information 193 are acquired by acquisition unit 110. Communication unit 130 transmits to server 200 a request to join any one of the group communications selected from the plurality of group communications by selection unit 120. Communication unit 130 may also transmit to server 200 a request to join a group communication selected by a user by input/output unit 140 (selection receiving unit). In this manner, the user can check a plurality of group communications that are candidates for participation, select a desired group communication from among them, and make a mid-session join request.

When the communication terminal 100 enters the communication range from outside the communication range, or when the communication terminal 100 that was conducting another communication ends the other communication, the communication unit 130 transmits a request to join the selected group communication to the server 200.

When the communication terminal 100 makes a request to start group communication as a calling terminal, the communication unit 130 transmits a start request including the group ID 1921 to the server 200 .

The input/output unit 140 has the functions of a display unit for displaying information about group communications, and a selection receiving unit for receiving, from a user, a selection of a group communication to participate in. The input/output unit 140 may be, for example, a touch panel capable of receiving a touch operation from a user.

The input/output unit 140 (display unit) displays information on the calling side when it acquires information from another communication terminal 100 or the server 200 or when it receives an incoming call. For example, when communication terminal 100e receives an incoming call from communication terminal 100a, the input/output unit 140 of communication terminal 100e displays the fact that the call has been received from communication terminal 100a by an application running on communication terminal 100e, a pop-up, a notification, or the like. Here, a speaker and a vibrator (both not shown) provided in communication terminal 100e may also be operated. The input/output unit 140 may refer to contact information 191 and display the name of the caller from the telephone number of the calling side, or the like.

Furthermore, the input/output unit 140 displays call history information 193 corresponding to at least one group communication that is a candidate for participation. Furthermore, when there are multiple candidate group communications, the input/output unit 140 displays the multiple pieces of call history information 193 in a predetermined order. The predetermined order may be, for example, an order based on the start date and time (call date and time), end date and time, number of calls, priority, importance, or urgency of the group call, as described above. In this way, the user can easily select a group communication to participate in.

4 is a diagram showing an example of a display screen 141 displayed on the input/output unit 140. Here, the input/output unit 140 displays the call history information 193 in reverse chronological order of the call date and time 1934 (see FIG. 3). As shown in the figure, the input/output unit 140 may display a session ID 1931, a target group ID 1932, a caller name, a call date and time 1934, and the like on the display screen 141. The input/output unit 140 may also display a display area 141a (for example, an "important" icon) showing a priority level, etc.

Note that instead of displaying all pieces of call history information 193 corresponding to group communications for which participation requests have been made, only a part of the call history information 193 may be displayed on the input/output unit 140. For example, when there are five incoming calls, the call history information 193 for three of them may be displayed according to the priority or the like. In this case, the remaining call history information 193 may be displayed in response to a touch operation from the user. The touch operation may include various operations such as tapping, swiping, dragging, or flicking.

The input/output unit 140 (selection receiving unit) receives from the user a selection of a group communication to join from among a plurality of group communications corresponding to the displayed plurality of pieces of call history information 193. The input/output unit 140 may display an operation display area 141b for receiving the selection from the user. The user can perform an operation on the communication terminal 100 by touching the operation display area 141b. In the example shown in FIG. 4, a "Join" button corresponding to each of the plurality of group communications is displayed as the operation display area 141b. The user can make a request to join the group communication by touching the "Join" button corresponding to the group communication in which the user wishes to join.

3, the description will be continued. The storage unit 190 is an example of a storage device such as a hard disk, a flash memory, etc. The storage unit 190 stores contact information 191, belonging group information 192, and call history information 193.

The contact information 191 is information for managing the contacts of a user. The contact information 191 may be, for example, information in which a contact ID 1911, a user name 1912, and a contact 1913 are associated with each other. The contact ID 1911 is information for identifying a contact. The user name 1912 is the name of the user corresponding to the contact. The contact 1913 may be the user's telephone number or the like. By registering such information in the storage unit 190 in advance, the user of the communication terminal 100 can check the telephone number and user name of the calling terminal on the input/output unit 140 when an incoming call is received. Not limited to this, the contact information 191 may include an image of the user or the like.

The belonging group information 192 is information for managing the belonging group to which the communication terminal 100 belongs. The belonging group information 192 may be, for example, information in which a group ID 1921 and an attribute 1922 are associated with each other. The group ID 1921 is information for identifying a group. The group ID 1921 corresponds to a group ID 2921 described later. The attribute 1922 is information indicating an attribute of the group. The attribute 1922 may be information indicating a classification according to a relationship with the members constituting the group, such as "work", "family", or "hobby". In addition, the attribute 1922 may be set in more detail according to the importance, such as "business (normal)" or "business (important project)". The attribute 1922 may be set arbitrarily according to a user operation.

The call history information 193 is information for managing the history of calls to the communication terminal 100. The call history information 193 may be, for example, information in which a session ID 1931, a target group ID 1932, a calling terminal ID 1933, and a call date and time 1934 are associated with each other. The call history information 193 may be acquired from session information included in an incoming call notification received from the server 200.

The session ID 1931 is information for identifying a session of group communication. The session ID 1931 is newly issued by the server 200 when group communication is started. The target group ID 1932 is the group ID of the group that is a target for participation in the session. Multiple group IDs may be associated with one session.

The calling terminal ID 1933 is information for identifying the calling terminal. For example, the calling terminal may be the communication terminal 100a that made the request to start the session. However, the calling terminal ID 1933 may be information for identifying the terminal that made the call when, for example, a call is made from a terminal other than the communication terminal 100a during group communication. The call date and time 1934 is information indicating the date and time when the communication terminal 100 was called to start the session.

Next, a description will be given of the configuration of the server 200. Fig. 5 is a block diagram showing the configuration of the server 200. The server 200 corresponds to the server 20 in the first embodiment. The server 200 includes a participation accepting unit 210, a determining unit 220, a communication unit 230, a session management unit 240, and a storage unit 290.

The participation acceptance unit 210 corresponds to the participation acceptance unit 21 in the first embodiment. The participation acceptance unit 210 accepts the participation of the communication terminal 100 in the group communication selected by the input/output unit 140 of the communication terminal 100. When the determination unit 220 determines that the group communication has already ended, the participation acceptance unit 210 may discard the participation request and suppress the start of a new group communication based on the participation request. In this manner, the process of mid-participation is not performed for the group communication that has already ended, and the process of allowing the communication terminal 100 to participate only in the ongoing group communication can be performed. In addition, the start of a new group communication unintended by the user can be prevented.

When the communication unit 230 receives a mid-join request to join a group communication from the communication terminal 100, the determination unit 220 determines whether the group communication is continuing based on the session ID 2931 included in the mid-join request. The determination unit 220 checks whether the end date and time 2936 of the group communication is stored by referring to the session information 293 corresponding to the session ID 2931. If the end date and time 2936 is stored, the determination unit 220 determines that the group communication is not continuing, and if not, determines that the group communication is continuing. Without being limited to this, the determination unit 220 may make the determination by referring to, for example, continuation state information indicating whether the group communication is continuing. For example, if a state such as "ongoing" or "ended" is stored in association with the session ID 2931, the determination unit 220 may make the determination by referring to this. The determination unit 220 outputs the determination result to the participation acceptance unit 210. If the group communication is not continuing, the determination unit 220 may cause the input/output unit 140 to display that fact.

The communication unit 230 communicates with the communication terminals 100a to 100e. For example, the communication unit 230 receives a request to start a group call from the calling communication terminal 100a, and calls the communication terminals 100b to 100e belonging to the group. The communication unit 230 also receives a notification from the communication terminal 100e that it has moved from outside the communication range to within the communication range, and transmits a missed call notification. The communication unit 230 also receives a mid-call join request from the communication terminal 100e.

The session management unit 240 manages a group communication session. When the communication unit 230 receives a request to start group communication, the session management unit 240 issues a new session ID 2931. The start request includes a group ID 1921 of the group that is the target of the group communication. The session management unit 240 refers to the group information 292 and acquires a terminal ID 2922 of a terminal belonging to the target group. The session management unit 240 refers to the terminal information 291 and controls the communication unit 230 to make a call based on the contact information 2913 of the terminal in the target group.

The session management unit 240 associates the session ID 2931 with information about the session and stores them in the storage unit 290. For example, the session management unit 240 associates the session ID 2931, the target group ID 2932, and the calling terminal ID 2933 and stores them as session information 293 in the storage unit 290. The target group ID 2932 is information for identifying a group that is to participate in the session, and is included in a request to start group communication. The calling terminal ID 2933 is information for identifying the calling terminal that has made a request to start the session. Here, the calling terminal ID 2933 may be information for identifying the communication terminal 100a.

Furthermore, if there is a communication terminal 100 that does not respond to a call, the session management unit 240 stores this in the session information 293 in association with the session ID 2931. For example, the session management unit 240 stores a non-responding terminal ID 2934 that identifies the communication terminal 100e that does not respond to a call in association with the session ID 2931. In this manner, the session management unit 240 can manage information about communication terminals 100 that are in a non-responding state because they did not respond at the start of a session.

The session management unit 240 associates the start date/time and end date/time of the session with the session ID 2931 and stores them in the session information 293 as start date/time 2935 and end date/time 2936, respectively. The session management unit 240 may acquire the start date/time and end date/time of the session from the communication terminal 100. The session management unit 240 may also receive information from the communication terminal 100 that group communication has started and ended, and store continuation status information of the group communication. The continuation status may be, for example, "started", "ongoing", "ended", etc.

The storage unit 290 is an example of a storage device such as a hard disk or a flash memory. The storage unit 290 stores terminal information 291, group information 292, and session information 293. The terminal information 291 is information for managing a plurality of communication terminals 100. The terminal information 291 may be information in which, for example, a terminal ID 2911, a user name 2912, and a contact point 2913 are associated with each other. The terminal ID 2911 is information for identifying a terminal. The user name 2912 is, for example, the name of a user who uses the terminal. Not limited to this, the user name 2912 may be information for identifying a user (for example, a user ID, etc.). The contact point 2913 may be, for example, a telephone number of each terminal.

Group information 292 is information for managing a group. Group information 292 may be, for example, information in which group ID 2921 and terminal ID 2922 are associated with each other. Group ID 2921 is information for identifying a group. Terminal ID 2922 is information for identifying a terminal belonging to the group. Terminal ID 2922 corresponds to terminal ID 2911. Since multiple terminals can belong to a group, multiple terminal IDs 2922 may be associated with one group ID 2921. Not limited to this, group information 292 may include attributes and the like, similar to belonging group information 192 in communication terminal 100.

The session information 293 is information for managing a session. The session information 293 may be information in which a session ID 2931, a target group ID 2932, a calling terminal ID 2933, a non-responding terminal ID 2934, a start date and time 2935, and an end date and time 2936 are associated with each other, for example.

The session ID 2931 is information for identifying a group communication session. The target group ID 2932 is information for identifying a group that is to participate in the session. A plurality of target group IDs 2932 may be associated with one session ID 2931. The calling terminal ID 2933 is information for identifying a terminal that has made a request to start the session. The unresponsive terminal ID 2934 is information for identifying a terminal that has not responded to a request to start the session. The start date and time 2935 is information indicating the start date and time of the session. The end date and time 2936 is information indicating the end date and time of the session.

Next, the processing performed by the communication system 1000 will be described with reference to the sequence diagrams shown in Fig. 6 and Fig. 7. As in the above description, it is assumed here that in a group of communication terminals 100a to 100e, communication terminal 100a makes a request to start group communication, communication terminals 100b to 100d respond, and communication terminal 100e is in an unresponding state at the start of group communication.

Fig. 6 shows the process when the communication terminal 100e becomes unresponsive because it is out of the communication range, and then becomes able to join the group communication midway because it moves into the communication range. Fig. 7 shows the process when the communication terminal 100e becomes unresponsive because it is performing another communication, and then becomes able to join the group communication midway because the other communication ends. Note that in Figs. 6 and 7, the description of the communication terminals 100c and 100d that perform the same operation as the communication terminal 100b is omitted.

First, the process of the communication system 1000 when the communication terminal 100e moves from outside the communication range to within the communication range will be described with reference to the sequence diagram shown in FIG. 6. First, the communication terminal 100a transmits a request to start group communication to the server 200 in the communication unit 130 (see FIG. 3) (S101). The transmitted request includes a group ID for identifying the group. The server 200 issues a new session ID in the session management unit 240 (see FIG. 5), associates it with the group ID, and stores it in the storage unit 290 as session information 293. The server 200 calls the communication terminals 100b to 100e belonging to the group in the communication unit 230. The server 200 transmits an incoming call notification to the communication terminals 100b to 100d that have responded, and the communication terminals 100b to 100d receive this (S102).

Here, since communication terminal 100e is outside the communication range, it does not respond to the call from server 200. Therefore, the communication from server 200 times out without receiving an incoming call notification from server 200 to communication terminal 100e (S103). Server 200 stores in session management section 240 the fact that there was no response from communication terminal 100e in association with the session ID (S104). Group communication is performed among communication terminals 100a to 100d (S105).

The communication terminal 100e moves from outside the communication range and returns to the communication range (S106). The communication terminal 100e transmits to the server 200, via the communication unit 130, a notification that the communication terminal 100e has returned to the communication range (S107). The server 200 transmits to the communication terminal 100e, via the communication unit 230, a missed call notification indicating that a request for the communication terminal 100e to participate in the group communication has been made (S108). The missed call notification may include session information including a session ID, a target group ID, a calling terminal ID, a call date and time, or a start date and time of the group communication. The missed call notification may be transmitted by the communication terminals 100a to 100d.

The communication terminal 100e selects a group communication to participate in by the selection unit 120 (S109). The selection unit 120 selects one of the group communications to participate in from at least one group communication that is a candidate to participate in, based on the session information included in the missed call notification. Here, the selection unit 120 selects the group communication requested to start by the communication terminal 100a as the group communication to participate in. If there is a call from multiple group communications, the selection unit 120 selects the group communication based on the start date and time and priority of the group communications. Without being limited to this, the input/output unit 140 may display a display screen as described with reference to FIG. 4 and accept the selection of the group communication to participate in from the user. The input/output unit 140 may display information about the selected group communication and notify the user.

The communication unit 130 transmits a mid-session join request to the selected group communication to the server 200 (S110). The communication unit 130 may transmit the mid-session join request in response to the user pressing a predetermined button on the input/output unit 140, or may transmit the mid-session join request automatically without user operation. For example, if the selection unit 120 is set in advance to select the last incoming group communication, the communication unit 130 may automatically make a call to the last incoming group communication without user operation. The mid-session join request includes the session ID of the group communication to be joined.

The server 200 receives the mid-join request from the communication terminal 100e, and the determination unit 220 determines whether the group communication is continuing or not (S111). The determination unit 220 acquires the session ID included in the mid-join request, and refers to the session information 293 of the group communication corresponding to the acquired session ID. The determination unit 220 determines that the group communication has ended if the end date and time 2936 of the group communication is stored, and determines that the group communication is continuing if not. The determination unit 220 may determine whether the group communication is continuing or not by referring to the continuing state information.

If the determination unit 220 determines that the group communication has ended (NO in S111), the server 200 causes the participation acceptance unit 210 to discard the participation request and suppress the start of a new group communication based on the participation request (S112). The input/output unit 140 may display, for example, "The group communication has already ended." Alternatively, the determination unit 220 may perform the determination before step S108. In this case, the selection unit 120 may select a group communication to participate in from among ongoing group communications and cause the input/output unit 140 to display it. In this way, the user can know which group communication to participate in, excluding group communications that have already ended.

If the determination unit 220 determines that the group communication is continuing (YES in S111), the server 200 causes the participation acceptance unit 210 to accept the participation of the communication terminal 100e in the selected group communication (S113). The communication terminal 100e joins the group communication midway, and group communication is performed among the communication terminals 100a to 100e (S114). The session management unit 240 stores in the session information 293 the fact that the communication terminal 100e has joined the group communication. The session management unit 240 may receive information from the communication terminal 100a or the like that the group communication has started and ended, and store the start date and time and the end date and time of the group communication in the session information 293. The session management unit 240 may store information that the group communication has ended in the session information 293, and update the continuation state information of the group communication.

Next, with reference to the sequence diagram shown in FIG. 7, a process will be described in which the communication terminal 100e that was performing another communication becomes able to join the group communication midway because the other communication has ended.

First, the communication terminal 100a transmits a request to start group communication to the server 200 through the communication unit 130 (see FIG. 3) (S201). The transmitted request includes a group ID for identifying the group. The server 200 issues a new session ID through the session management unit 240 (see FIG. 5), associates it with the group ID, and stores it in the storage unit 290 as session information 293. The server 200 calls the communication terminals 100b to 100e belonging to the group through the communication unit 230. The server 200 transmits an incoming call notification to the communication terminals 100b to 100d that have responded, and the communication terminals 100b to 100d receive this (S202).

The communication terminal 100e receives an incoming call notification from the server 200 at the communication unit 130 (S203). However, the communication terminal 100e does not respond to the call from the server 200 because it is performing another communication. The communication terminal 100e acquires session information included in the incoming call notification at the acquisition unit 110 and stores it in the storage unit 190 as the call history information 193 (S204). The session information may include a session ID, a target group ID, a calling terminal ID, a call date and time, or a start date and time of the group communication. Group communication is performed between the communication terminals 100a to 100d (S205).

The communication terminal 100e ends the other communication (S206). The communication terminal 100e selects a group communication to participate in by using the selection unit 120 (S207). Step S207 is similar to step S109 shown in FIG. 6, and therefore a detailed description thereof will be omitted.

The communication unit 130 transmits a mid-session join request to the selected group communication to the server 200 (S208). The communication unit 130 may transmit the mid-session join request in response to the user pressing a predetermined button on the input/output unit 140, or may transmit the mid-session join request automatically without user operation. As in step S110 shown in Fig. 6, the communication unit 130 may automatically make a call to the last incoming group communication, for example. The mid-session join request includes the session ID of the group communication to be joined.

The server 200 receives the mid-session request from the communication terminal 100e, and the determination unit 220 determines whether the group communication is continuing (S209). The method of determination is the same as that of step S111 shown in FIG. 6, and therefore a detailed description thereof will be omitted. If the determination unit 220 determines that the group communication has ended (NO in S209), the server 200 discards the participation request in the participation acceptance unit 210 and suppresses the start of a new group communication based on the participation request (S210). The determination unit 220 may monitor the continuation state of the group communication corresponding to the incoming call notification transmitted in step S203. When the group communication for which the incoming call notification has been transmitted has ended, the determination unit 220 may transmit that fact to the communication terminal 100e and display it on the input/output unit 140. In this way, the user can know the group communication to be participated in, excluding the group communication that has already ended.

If the determination unit 220 determines that the group communication is continuing (YES in S209), the server 200 causes the participation acceptance unit 210 to accept the participation of the communication terminal 100e in the selected group communication (S211). The communication terminal 100e joins the group communication midway, and group communication is performed among the communication terminals 100a to 100e (S212). The session management unit 240 stores in the session information 293 the fact that the communication terminal 100e has joined the group communication. The session management unit 240 may receive information from the communication terminal 100a or the like that the group communication has started and ended, and store the start date and time and the end date and time of the group communication in the session information 293. The session management unit 240 may store information that the group communication has ended in the session information 293, and update the continuation state information of the group communication.

As described above, in the communication system 1000 according to the present embodiment, the communication terminal 100e that did not respond to the call at the start of the group communication acquires information about the group communication from the server 200. The selection unit 120 of the communication terminal 100e selects one of the group communications from at least one group communication that is a candidate for mid-way participation based on the acquired information. When multiple pieces of information about group communications are acquired, the selection unit 120 selects one of the group communications based on the multiple pieces of information according to the start date and time of the group communication, the priority, and the like. In addition, the input/output unit 140 of the communication terminal 100e displays multiple group communications in a predetermined order according to the date and time of the call, the priority of the group communication, and the like, and accepts a selection from the user. In this way, the user can easily select a group communication to participate in.

The communication terminal 100e can make a mid-join request in the manner described above both when it moves from outside the communication range to within the communication range, and when it was in the middle of another communication but that communication ends, so that it can more reliably join mid-group communication.

&lt;Example of Hardware Configuration&gt; Each functional component of the communication terminal 100 and the server 200 may be realized by hardware that realizes each functional component (e.g., a hardwired electronic circuit, etc.), or may be realized by a combination of hardware and software (e.g., a combination of an electronic circuit and a program that controls it, etc.). Below, a further explanation will be given of the case where each functional component of the communication terminal 100, etc. is realized by a combination of hardware and software.

8 is a block diagram illustrating a hardware configuration of a computer 900 that realizes the communication terminal 100, etc. The computer 900 may be a dedicated computer designed to realize the communication terminal 100, etc., or may be a general-purpose computer. The computer 900 may be a portable computer such as a smartphone or a tablet terminal.

For example, by installing a specific application in the computer 900, the computer 900 realizes each function of the communication terminal 100, etc. The application is constituted by a program for realizing the functional components of the communication terminal 100, etc.

The computer 900 includes a bus 902, a processor 904, a memory 906, a storage device 908, an input/output interface 910, and a network interface 912. The bus 902 is a data transmission path for the processor 904, the memory 906, the storage device 908, the input/output interface 910, and the network interface 912 to transmit and receive data to and from each other. However, the method of connecting the processor 904 and other components to each other is not limited to a bus connection.

The processor 904 is one of various processors such as a central processing unit (CPU), a graphics processing unit (GPU), or a field-programmable gate array (FPGA). The memory 906 is a main storage device realized using a random access memory (RAM) or the like. The storage device 908 is an auxiliary storage device realized using a hard disk, a solid state drive (SSD), a memory card, or a read only memory (ROM) or the like.

The input/output interface 910 is an interface for connecting the computer 900 to an input/output device. For example, the input/output interface 910 is connected to an input device such as a keyboard and an output device such as a display device.

The network interface 912 is an interface for connecting the computer 900 to a network. This network may be a local area network (LAN) or a wide area network (WAN).

The storage device 908 stores a program (a program that realizes the above-mentioned application) that realizes each functional component of the communication terminal 100, etc. The processor 904 reads this program into the memory 906 and executes it to realize each functional component of the communication terminal 100, etc.

Each of the processors executes one or more programs, each of which includes instructions for causing a computer to execute an algorithm. The programs can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic storage media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical storage media (e.g., magneto-optical disks), optical disk media such as compact discs (CDs) or digital versatile discs (DVDs), and semiconductor memories (e.g., mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, RAMs). The programs can also be stored and provided to a computer using various types of transitory computer readable media. The program may be provided to the computer via a temporary computer-readable medium. Examples of the temporary computer-readable medium include an electric signal, an optical signal, and an electromagnetic wave. The temporary computer-readable medium can provide the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

The present disclosure is not limited to the above-described embodiments, and may be modified as appropriate without departing from the spirit and scope of the present disclosure.

A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes.

(Supplementary Note 1) A communication system comprising a communication terminal and a server that controls group communication among a plurality of the communication terminals, wherein the communication terminal has an acquisition means that acquires information regarding a group communication that has already been started among the plurality of communication terminals and is in an unresponsive state because it did not respond at the start, a selection means that selects one of at least one of the group communications that is a candidate for participation based on the acquired information, and a transmission means that transmits a participation request for the selected group communication to the server, and the server has a participation acceptance means that accepts the participation of the communication terminal in the selected group communication.

(Appendix 2) The communication system described in Appendix 1, wherein the transmission means transmits a request to join the selected group communication to the server when the communication terminal enters a communication range from outside the communication range, or when the communication terminal that was conducting another communication ends the other communication.

(Appendix 3) A communication system as described in appendix 1 or 2, wherein the acquisition means acquires a plurality of the information, and the selection means selects one of the group communications from at least one of the group communications that is a candidate for participation based on the acquired plurality of the information.

(Appendix 4) The communication system described in Appendix 3, wherein the selection means selects one of at least one of the group communications that is a candidate for participation based on start date and time information of the group communications contained in the acquired multiple pieces of information.

(Supplementary Note 5) The communication terminal further comprises a display means for displaying the information corresponding to at least one of the group communications that are candidates for participation in, and a selection receiving means for receiving from the user a selection of the group communication to participate in from the at least one of the group communications that are candidates for participation in, wherein the display means, when there are multiple pieces of information corresponding to the at least one of the group communications that are candidates for participation in, displays the multiple pieces of information in a predetermined order, the selection receiving means receives from the user a selection of the group communication to participate in from the multiple pieces of information related to the at least one of the group communications that are candidates for participation in displayed, and the transmission means transmits a request to participate in the group communication selected by the selection receiving means to the server.

(Appendix 6) The server further has a determination means for determining whether the selected group communication is continuing, and the participation accepting means, when it is determined that the selected group communication has already ended, discards the participation request and suppresses the start of a new group communication based on the participation request. The communication system described in any one of Appendices 1 to 5.

(Supplementary Note 7) A communication terminal comprising: an acquisition means for acquiring information regarding a group communication that has already been started between a plurality of communication terminals and is in an unresponsive state due to not responding at the start of the group communication; a selection means for selecting one of the group communications from at least one of the group communications that is a candidate for joining based on the acquired information; and a transmission means for transmitting a request to join the selected group communication to a server that controls the group communication between the plurality of communication terminals.

(Appendix 8) The communication terminal according to Appendix 7, wherein the transmission means transmits a request to join the selected group communication to the server when the communication terminal enters a communication range from outside the communication range, or when the communication terminal that was conducting another communication ends the other communication.

(Appendix 9) A communication method comprising: acquiring information about a group communication that has already been started between a plurality of communication terminals and is in an unresponsive state because it did not respond at the time of initiation; selecting one of at least one of the group communications that is a candidate for joining based on the acquired information; and transmitting a request to join the selected group communication to a server that controls the group communication between the plurality of communication terminals.

(Supplementary Note 10) A non-transitory computer-readable medium storing a communication program that causes a computer to execute the following steps: an acquisition process for acquiring information about a group communication that has already been started between a plurality of communication terminals and is in an unresponsive state because it did not respond at the start of the group communication; a selection process for selecting one of the group communications from at least one of the group communications that is a candidate for joining based on the acquired information; and a transmission process for transmitting a request to join the selected group communication to a server that controls the group communication between the plurality of communication terminals.

1 Communication Systems

10 Communication terminal

11 Acquisition Department

12 Selection

13 Transmitter

20 server

twenty one Participant reception desk

100, 100a to 100e communication terminal

110 Acquisition Department

120 Selection

130 Communications Department

140 Input/Output Section

141 Display Screen

141a Display area

141b Operation display area

190 Memory section

191 Contact Information

1911 Contact ID

1912 Username

1913 contact address

192 Group information

1921 Group ID

1922 attribute

193 Call history information

1931 Session ID

1932 Target Group ID

1933 Caller's terminal ID

1934 Call date and time

200 server

210 Participant reception desk

220 Judgment section

230 Communications Department

240 Session Management Unit

290 Memory section

291 Device information

2911 Device ID

2912 Username

2913 contact address

292 Group Information

2921 Group ID

2922 Device ID

293 Session Information

2931 Session ID

2932 Target Group ID

2933 Caller's terminal ID

2934 Unresponsive device ID

2935 Start date and time

2936 End date and time

300 Base Station

900 computer

902 bus

904 Processor

906 Memory

908 Storage Devices

910 Input/Output Interface

912 Network Interface

1000 Communication Systems

N Network