A method of controlling a portable device including a first touch screen and a second touch screen arranged on at least one foldable panel, the method comprising: displaying first information comprising at least one application icon including a first application icon associated with an execution of a call application on the first touch screen and displaying second information on the second touch screen in a state where a first panel including the first touch screen and a second panel including the second touch screen are unfolded; detecting a touch gesture on the first application icon; displaying an outgoing call screen provided by the call application in replacement of the first information in response to the detection of the touch gesture, the outgoing call screen including at least one of a number display area, a keypad area, a call key, avideo call key, and a message sending key, and controlling the second touch screen to maintain a display of the second information while the outgoing call screen is displayed on the first touch screen; displaying a contact number which is input through the keypad area and detecting a tap gesture on the call key to start a dialing function for the contact number; displaying a dialing screen on the first touch screen in replacement of the outgoing call screen in response to a detection of the tap gesture, and displaying a guide message screen of advising to fold the portable device for a private call with a user of the contact number on the second touch screen while displaying the dialing screen on the first touch screen; connecting the call in a speaker-phone mode if the call is connected with the counterpart call participant in a state where the first panel including the first touch screen and the second panel including the second touch screen are unfolded; and in response to detecting that the portable device is folded-out, switching to a private call mode wherein a volume of a speaker and a sensitivity of a microphone are relatively decreased to allow a call to be performed having the portable device close to the ear and mouth of a user of the portable device. displaying first information comprising at least one application icon including a first application icon associated with an execution of a call application on the first touch screen and displaying second information on the second touch screen in a state where a first panel including the first touch screen and a second panel including the second touch screen are unfolded; detecting a touch gesture on the first application icon; displaying an outgoing call screen provided by the call application in replacement of the first information in response to the detection of the touch gesture, the outgoing call screen including at least one of a number display area, a keypad area, a call key, avideo call key, and a message sending key, and controlling the second touch screen to maintain a display of the second information while the outgoing call screen is displayed on the first touch screen; displaying a contact number which is input through the keypad area and detecting a tap gesture on the call key to start a dialing function for the contact number; displaying a dialing screen on the first touch screen in replacement of the outgoing call screen in response to a detection of the tap gesture, and displaying a guide message screen of advising to fold the portable device for a private call with a user of the contact number on the second touch screen while displaying the dialing screen on the first touch screen; connecting the call in a speaker-phone mode if the call is connected with the counterpart call participant in a state where the first panel including the first touch screen and the second panel including the second touch screen are unfolded; and in response to detecting that the portable device is folded-out, switching to a private call mode wherein a volume of a speaker and a sensitivity of a microphone are relatively decreased to allow a call to be performed having the portable device close to the ear and mouth of a user of the portable device.