Abstract: A buffer memory, an electrically erasable and writable ROM, a capacitor for holding a voltage, and a voltage detection circuit for detecting the voltage of a battery for a power source are provided in a portable telephone unit. During conversation, data to be saved is written into the buffer memory. At the time of ending the conversation, the data written in the buffer memory is transferred to a ROM and written therein. When the voltage detection circuit detects that the voltage of the battery is unobtainable, the buffer memory and the ROM are operated and the data written in the buffer memory is also transferred to the ROM and written therein by the voltage held in the capacitor.

Abstract: In a radio communication apparatus, a counter is reset to its initial state if the user of the apparatus responds to an alert tone representative of call incoming, or caused to count the number of times of call incoming if the user does not respond. The number of times of call incoming occurred without any user's response and a reference value are compared. If the number of times counted and reference value compare equal, the volume of the alert tone is increased for the current call incoming or for the next call incoming. Further, If the user does not respond to the call incoming, a timer starts counting time. When call incoming is repeated within a preselected period of time, the volume of the alert tone is increased. Loudening the alert tone may be replaced with changing the pattern of the alert tone.