Abstract: Provided is a call control method executed by a computer of an operation terminal to execute a process. The process includes generating an identifier of a group call, notifying a management server of the group call of the identifier, transmitting the identifier and a first call of a first conversation partner to a first terminal of the first conversation partner belonging to the plurality of conversation partners, displaying a call screen of the group call on the operation terminal and transmitting the identifier and a second call of a second conversation partner to a second terminal of the second conversation partner belonging to the plurality of conversation partners when participation of the first conversation partner in the group call is notified from the management server, and updating the call screen when participation of the second conversation partner in the group call is notified from the management server.