Mobile Communication System and Mobile Unit

A mobile station capable of communicating with a plurality of communication networks operated by different carriers, and reporting its radio capability to each of said plurality of communication networks, said mobile station comprising:

• a control section for carrying out communication control with said plurality of communication networks, said control section including:
• communication network search means for searching for a communication network capable of communicating with said mobile station from said plurality of communication networks;
• communication network decision means for deciding, from said communication networks capable of communicating with said mobile station, a to-be-connected communication network based on a communication network decision internal list stored in advance;
• radio capability selection means for selecting, according to detailed information on the to-be-connected communication network determined by said communication network decision means and according to information on services to be used, a radio capability value for each or part of a plurality of radio capability items in a radio capability internal list stored in advance;
• and
• radio capability report means for reporting to said communication network a radio capability report list composed of a plurality of radio capability values selected by said radio capability selection means;
• a memory section including the communication network decision internal list and the radio capability internal list as part of proper information;
• and
• a radio section under control of said control section for carrying out the communication network search and radio capability report, and for transmitting and receiving the radio capability report list with said to-be-connected communication network via a radio interface.