Abstract: In a telephone apparatus used for a telephone system such that the telephone set is connected to a remote destination telephone set through telephone circuits after an ID number of a subscriber has been transmitted to the telephone company, the handset comprises a key entry section including plural dial keys, a memory section for storing the ID number and destination telephone numbers, a display section for displaying a destination telephone number corresponding to an operated dial key, and a control section for enabling a display of the ID number when the ID number is written but disabling a display of the ID number when read. Since the ID number is not displayed while being read to transmit it to the telephone company, the ID number of the subscriber is kept secret from others.