CONTROL APPARATUS, CONTROL METHOD, COMMUNICATION SYSTEM AND PROGRAM

A control apparatus includes: a determination unit that determines whether identification information for identifying a mobile communication terminal in a second mobile communication network can be changed from first identification information assigned in the first mobile communication network to a second identification information assigned in the second mobile communication network, when the mobile communication terminal in which the first identification information is stored is situated in a region in which the second mobile communication network can be used and the mobile communication terminal uses the first mobile communication network via a second mobile communication network; and a notification unit that transmits a notification of a change of the identification information to a request apparatus that is connected to the second mobile communication network and is configured to request the mobile communication terminal to change the identification information, if it is determined that the identification information can be changed.