Patent ID: 8121643

Claim:
A system with a first subscriber identity card, a second subscriber identity card and a radio frequency (RF) module, comprising: a controller initiating a first operating voltage of the first subscriber identity card and initiating a second operating voltage of the second subscriber identity respectively, and a Baseband unit cooperating with the first subscriber identity card to camp on a first cell and cooperating with the second subscriber identity card to camp on a second cell via the RF module, wherein the controller provides a voltage variable signal to the first subscriber identity card and the second subscriber identity card and receives a first code from the first subscriber identity card and a second code from the second subscriber identity card when the voltage variable signal is asserted, and the Baseband unit provides a first setting signal corresponding to the first code to initiate the first operating voltage of the first subscriber identity card, and provides a second setting signal corresponding to the second code to the controller to initiate the second operating voltage of the second subscriber card.