A foldable mobile communication terminal and a calling method thereof, in which calling operation to a telephone number is started from the open state of its cabinet, and the calling operation is executed smoothly by reducing one of processes of the calling operation. Data communication is executed at the open state of its cabinet and voice communication is executed at the closed state of the cabinet, provides an inner side displaying section for displaying data inputted or received at the open state of the cabinet, a calling number input buffer for storing data of a telephone number displayed on the inner side displaying section, and a voice communication changing-over section for changing-over from the data communication to the voice communication to the telephone number storing in the calling number input buffer, when a state, which the cabinet was closed from the open state of the cabinet, is detected.