To perform power saving operation of a terminal device flexibly in accordance with the situation or setting.

An SIP server 12 comprises a terminal state table 28 storing judgement information for judging whether or not a connection request from a mobile terminal of a transmission source to a mobile terminal of a call termination destination is to be transmitted to the mobile terminal of the destination, receives the connection request from the mobile terminal of the transmission source to the mobile terminal of the destination, and judges whether or not the connection request is to be transmitted to the mobile terminal of the destination based on the judgement information, relating to the mobile terminal of the destination, contained in the terminal state table 28 by referring to the table. A mobile terminal 16 is capable of performing power saving operation and requests the SIP server 12 to register, in the terminal state table 28, that the connection request is not transmitted to the mobile terminal 16 during the power saving operation.