A portable terminal can analyze a voice of the other party and update a phonebook. A voice pattern can be extracted from an incoming voice signal. A determination is made whether the extracted voice pattern is contained in a list of voice patterns stored in the portable terminal. If the extracted voice pattern is contained in the list, a determination is made whether a stored phone number matches a received phone number. If the stored phone number is not identical to the received phone number, the stored phone number is changed with the received phone number. Therefore, the phonebook can be automatically (e.g., without user input) updated although the user does not directly change and store phone numbers of other parties.