There is provided a method of alerting a user of an occasion date in a phone having an idle mode screen displaying function and an incoming call ring sound alteration function. It is first determined whether today is a registered occasion date. If today is not the registered occasion date, a first predetermined image is set for an idle mode screen and a first predetermined ring sound is set as an incoming call ring sound. On the other hand, if the today is the registered occasion date, the first predetermined image is changed to a second predetermined image for the idle mode screen and the first predetermined ring sound is changed, to a second predetermined ring sound in place of the incoming call ring sound.