A communication apparatus is provided. A first subscriber identity card is with a first address and camps on a first cell. A second subscriber identity card is with a second address and camps on a second cell. A processor determines whether a first communication status of the first subscriber identity card reaches a first limitation, determines whether a second communication status of the second subscriber identity card reaches a second limitation, and determines whether to activate a service instructing the first wireless network to transfer a first apparatus terminated communication request of the first subscriber identity card to the second subscriber identity card according to determination results for the first communication status and the second communication status, wherein the first apparatus terminated communication request is initiated from a peer communication entity to request for establishing wireless communication with the first subscriber identity card.