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 storage unit manages a receiving order by storing a received call processing message. A retention unit retains key information, which is included in the call processing message, and element information, which is correlated to the key information and included in the call processing message, by updating the two pieces of information for every key information at every time when receiving the call processing message. A call processing execution unit carries out a call processing for each call processing message stored by the storage unit at a predetermined time interval in a lump based on the key information and element information stored by the retention unit.

Abstract: A communication state between a session initiation protocol server and another session initiation protocol server to be a destination for transmitting a request message is determined. When it is determined that the communication state is in a communication unavailable state, a subsequent session initiation protocol server of the session initiation protocol server designated as the destination is determined to be a new destination based on information on a relay order of the session initiation protocol servers set in header information of the request message.

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 server capable of reducing an overloaded state even if a refreshing message is frequently generated. A central processing unit receives a first message transmitted from a terminal to establish a session. The central processing unit, when receiving the first message from the terminal, allocates to itself and the other plural central processing units the subsequent message transmission and reception between the terminal and a terminal as a communication partner. The central processing unit allocates to itself and the other plural central processing units the message transmission and reception between the terminals, for example, in a round robin fashion.

Abstract: A storage unit manages a receiving order by storing a received call processing message. A retention unit retains key information, which is included in the call processing message, and element information, which is correlated to the key information and included in the call processing message, by updating the two pieces of information for every key information at every time when receiving the call processing message. A call processing execution unit carries out a call processing for each call processing message stored by the storage unit at a predetermined time interval in a lump based on the key information and element information stored by the retention unit.

Abstract: Using a transaction established between SSP and SCP or DB for each call, an subnode (DB or SSP) address and transaction identifier are transmitted to the SCP or DB, thereby permitting direct communications between the SSP and DB. This serves to alleviate the processing load of the SCP and reduce traffic in a signaling network when the SCP processes a service request from the SSP in cooperation with the DB.