A communication apparatus is provided. A first subscriber identity card camps on a first cell. A second subscriber identity card camps on a second cell. A processor obtains information regarding first paging occasions distributed within a predetermined time interval for the first subscriber identity card, obtains information regarding second paging occasions distributed within the predetermined time interval for the second subscriber identity card, detects a forthcoming time slot of the predetermined time interval in which one of the first paging occasions collides with one of the second paging occasions, determines listening to one of the first cell and the second cell in the detected time slot, and notifies of the determination to the radio transceiver module so as to direct the radio transceiver module to listen to the determined cell to receive a corresponding paging message from the determined cell in the detected time slot.