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

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 includes:

at least one memory storing instructions; and

at least one processor configured to execute the instructions to:

acquire information regarding group communication that has already been started among the plurality of communication terminals and is in a non-answered state due to no answer at the start;

select any one from one or more group communications that are candidates for participation based on the acquired information; and

when the communication terminal that was performing another communication has ended the another communication, transmit a participation request for the selected group communication to the server, and

the server includes:

at least one memory storing instructions; and

at least one processor configured to execute the instructions to accept participation of the communication terminal in the selected group communication.

2 . The communication system according to claim 1 , wherein the at least one processor of the communication terminal is further configured to execute the instructions to, when the communication terminal has entered a communication range from outside the communication range, transmit the participation request for the selected group communication to the server.

3 . The communication system according to claim 1 , wherein

the at least one processor of the communication terminal is further configured to execute the instructions to:

acquire a plurality of pieces of the information; and

select any one from one or more group communications that are the candidates for participation based on the plurality of pieces of acquired information.

4 . The communication system according to claim 3 , wherein

the at least one processor of the communication terminal is further configured to execute the instructions to select any one from one or more group communications that are the candidates for participation based on start date and time information of the group communications included in the plurality of pieces of acquired information.

5 . The communication system according to claim 1 , wherein

the at least one processor of the communication terminal is further configured to execute the instructions to:

display the information corresponding to one or more group communications that are the candidates for participation; and

receive, from a user, selection of the group communication to participate in from one or more group communications that are the candidates for participation,

the at least one processor of the communication terminal is further configured to execute the instructions to:

when there are a plurality of pieces of the information corresponding to one or more group communications that are the candidates for participation, display the plurality of pieces of information in a predetermined order;

receive, from the user, selection of the group communication to participate in based on the plurality of pieces of displayed information regarding one or more group communications that are the candidates for participation; and

transmit a participation request for the selected group communication to the server.

6 . The communication system according to claim 1 , wherein

the at least one processor of the server is further configured to execute the instructions to:

determine whether or not the selected group communication is being continued; and

when it is determined that the selected group communication has already ended, discard the participation request and suppress start of new group communication based on the participation request.

7 . A communication terminal comprising:

at least one memory storing instructions; and

at least one processor configured to execute the instructions to:

acquire information regarding group communication that has already been started among a plurality of communication terminals and is in a non-answered state due to no answer at the start;

select any one from one or more group communications that are candidates for participation based on the acquired information; and

when the communication terminal that was performing another communication has ended the another communication, transmit a participation request for the selected group communication to a server that controls the group communication among the plurality of communication terminals.

8 . The communication terminal according to claim 7 , wherein the at least one processor is further configured to execute the instructions to, when the communication terminal has entered a communication range from outside the communication range, transmit the participation request for the selected group communication to the server.

9 . A communication method comprising:

acquiring information regarding group communication that has already been started among a plurality of communication terminals and is in a non-answered state due to no answer at the start;

selecting any one from one or more group communications that are candidates for participation based on the acquired information; and

when a communication terminal, from the plurality of communication terminals, that was performing another communication has ended the another communication, transmitting a participation request for the selected group communication to a server that controls the group communication among the plurality of communication terminals.