When a connection control device determines that the connection control device is in a congested state, based on whether a usage of at least one of hardware resources necessary for call processing to establish a call connection is equal to or more than a predetermined threshold value, the CPU of the connection control device forcefully disconnects an established call connection after a connection available time elapses, and, when an INVITE message is transmitted from a terminal device, the CPU of the connection control device receives the INVITE message, calculates the wait time, creates and transmits a response message stating the wait time, and stores the message as a reserved call on a reservation list.