The mobile telephone includes (a) a detector which transmits a detection signal when the detector detects that the mobile telephone is in a stand-by mode where the mobile telephone waits receiving a radio signal from a base station, and that the mobile telephone is located out of a service area, (b) a timer which starts measuring a period of time in which the mobile telephone keeps located out of the service area, on receipt of the detection signal, and (c) at least one annunciator which makes at least one of sounds and vibration. The detector annunciates that the mobile telephone keeps located out of the service area for a predetermined first period of time, when the mobile telephone is in a stand-by mode, to a user through the annunciator, when a period of time measured by the timer reaches the predetermined first period of time.