A communication apparatus is provided. A first subscriber identity card camps on a first cell belonging to a first wireless network via a radio transceiver module and stores first contact entries each having a destination address. A second subscriber identity card camps on a second cell belonging to a second wireless network via the radio transceiver module and stores second contact entries each having a destination address. A processor receives an apparatus originated communication request with a destination address, determines whether the received destination address is currently stored in one of the first contact entries of the first subscriber identity card or one of the second contact entries of the second subscriber identity card, and transmits the apparatus originated communication request to the cell that the determined subscriber identity card camps on to establish a wireless communication with a peer device associated with the received destination address.