A mobile station is a device that users use directly to complete mobile communication. For digital mobile communication, it was a certain degree of personal characteristics - that is, the separation of the SIM card with the user's private information and the physical implementation of the communication device. The SIM card contains all information on the side of the wireless interface that is available to the user, as well as information about the authentication and encryption implementation, while the physical device can be a handheld, on-board computer or a mobile terminal that consists directly is connected to the terminal.