An object of the present invention is to be able to rejoin a group call by spontaneous operation from the terminal side at an optional timing.The group call server provides a plurality of mobile communications terminals with a function of a group call between the terminals through a communications network, and comprises: an ID granting unit that grants the group call to be established a call ID that identifies the group call; an ID notification unit that gives the terminals participating in the group call to be established the call ID granted to the group call by the ID granting unit; a rejoin request receiving unit that receives requests to rejoin the group call that have been transmitted from a terminal disconnected from the group call and that include the call ID; and a rejoin control unit that allows the terminal that transmitted the request to rejoin the group call related to the call ID included in the rejoin request received by the rejoin request receiving unit.