As a network control device which controls a call connection between a calling party terminal and a called party terminal, a network control device determines whether the own network control device is in a congestion state when a handover request is acquired from another network control device which is in the congestion state, and stops transmitting a busy tone to a mobile terminal which is the calling party terminal and transmits a ring back tone to the mobile terminal when it is determined that the own network control device is not in the congestion state.