A system for initiating operating voltages for subscriber identity cards is provided. The system includes a first subscriber identity card, a second subscriber identity card, an RF module, a controller and a Baseband unit. The controller initiates a first operating voltage of the first subscriber identity card and initiates a second operating voltage of the second subscriber identity, respectively. The Baseband unit cooperates with the first subscriber identity card to camp on a first cell and cooperates with the second subscriber identity card to camp on a second cell via the RF module.