Abstract: 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.

Abstract: A call management method makes a call management system perform a process of releasing resources that are secured for a terminal device that has become a communication disable state among resources in the call management system that are secured for each of the terminal devices under speech communication (#103 and #108), and sending a message for finishing speech communication to a terminal device on the other end of the speech communication without transmitting it to the terminal device that has become a communication disable state (#112), when it is detected that one of the terminal devices under speech communication with each other has become a communication disable state in a mobile communication network (#102).

Abstract: A call management method makes a call management system perform a process of releasing resources that are secured for a terminal device that has become a communication disable state among resources in the call management system that are secured for each of the terminal devices under speech communication (#103 and #108), and sending a message for finishing speech communication to a terminal device on the other end of the speech communication without transmitting it to the terminal device that has become a communication disable state (#112), when it is detected that one of the terminal devices under speech communication with each other has become a communication disable state in a mobile communication network (#102).

Abstract: 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.