A communication apparatus is provided. A first subscriber identity card camps on a first cell belonging to a first wireless network via at least one radio transceiver module. A second subscriber identity card camps on a second cell belonging to a second wireless network via the radio transceiver module. A memory device stores information indicating at least one discount period of the first wireless network and at least one discount period of the second wireless network. A processor receives an apparatus originated communication request with a destination address, determines whether a current time falls within the discount period of the first wireless network or the discount period of the second wireless network, and establishes a wireless communication with a peer device of the received destination address through one of the first cell or the second cell in response to the fallen discount period.