A mobile communication device including a Baseband processor is provided. The Baseband processor is configured to determine whether the mobile communication device is operating in an idle mode or a connected mode with a first service network in response to starting a Circuit Switch Fallback (CSFB) call, search for a cell of a second service network on a frequency, on which the mobile communication device has previously made another CSFB call successfully from the first service network, when the mobile communication device is operating in the idle mode with the serving cell, and make the CSFB call on the cell.