Apparatus for displaying time-of-day data adaptively to different time zones

A cellular mobile telephone set operable in a telephone mode and a time data display mode, said telephone set including a receiver for receiving area identifying codes transmitted from a cellular mobile communications system and a keypad, comprising:

• a timepiece for constantly generating time-of-day data;
• a memory;
• write control means responsive to said receiver during said time data display mode for storing a plurality of successive time difference data entered from said keypad into said memory respectively corresponding to area identifying codes successively received by said receiver;
• read control means responsive to said receiver during said time data display mode for recalling one of the stored time difference data from said memory corresponding to an area identifying code received by said receiver and modifying said time-of-day data with the recalled time difference data;
• and
• a display for displaying the modified time-of-day data.