A transition control method to be performed in a communication system including a mobile communication device that performs mobile communication and a transition control device that controls a transition between mobile communication networks over which the mobile communication device performs mobile communication, the mobile communication device including an attachment unit for attaching thereto a subscriber authentication module that stores therein first connection information and second connection information, the first connection information corresponding to a mobile communication network and being necessary for performing mobile communication over the mobile communication network, the second connection information being necessary for performing communication with a connection information management server provided corresponding to a mobile communication network and configured to perform rewrite control on the first connection information, the transition control method comprising:
- a transition request input step, by the transition control device, of inputting a transition request to make a transition between mobile communication networks over which the mobile communication device performs mobile communication;
- a first transmission step, by the transition control device, of transmitting the second connection information associated with a connection information management server corresponding to a destination mobile communication network, to the mobile communication device associated with the transition request input in the transition request input step, through a source mobile communication network;
- a first reception step, by the mobile communication device, of receiving the second connection information transmitted in the first transmission step through the source mobile communication network, and storing the received second connection information in the subscriber authentication module;
- a second transmission step, by the transition control device, of generating the first connection information associated with the destination mobile communication network for the mobile communication device associated with the transition request input in the transition request input step, and transmitting the generated first connection information to the connection information management server corresponding to the destination mobile communication network;
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- a second reception step, by the mobile communication device, of performing communication directly with the connection information management server corresponding to the destination mobile communication network, using the second connection information received in the first reception step and stored in the subscriber authentication module attached by the attachment unit, to receive the first connection information associated with the destination mobile communication network that is transmitted to the connection information management server in the second transmission step, and storing the received first connection information in the subscriber authentication module.