To provide a data communication system which lightens processing related to changes in the status in signaling processing performed between terminals. A signaling server communicating mutually with a plurality of terminals includes: a transmitting/receiving part for transmitting/receiving a message; a status management part for updating a registered terminal list and status management information; and a signaling processing part for judging a destination and a type of the message received at the transmitting/receiving part. The signaling processing part gives an instruction to the status management part to update the status management information in accordance with contents of the message without transferring the message to a first terminal, when the first terminal requires the signaling processing support and the message is not directly related to starting or stopping of communication with the first terminal.