Abstract: A personal data security system and method for hand held devices are resolved for only locking all the applications or the personal data at a time, or to not lock a single application/function or port of the information in the hand held device quickly. The hand held device has a locking/unlocking function module to provide a locking function or an unlocking function, to make the locked personal data or the locked applications/functions are not displayed or executed on the hand held device. Via long pressing at least two of the buttons simultaneously or inputting the buttons sequentially executes the locking function and sets one of the secret levels of the applications/functions or the personal data. When user inputting one secret unlocking code is executed the unlocking function to unlock the locked applications/functions or the locked personal data, thereby the hand held device is achieved to the personal data security.

Abstract: A method of identifying a second caller when a handheld device is busy with a first caller, comprising the steps of: (a) receiving an ID from the second caller; (b) comparing the ID of the second caller with an ID database of the handheld device for finding out corresponding call waiting data; and (c) outputting a call-waiting signal corresponding to the call waiting data. Hence the method can alert a mobile phone user via a sound signal, a light signal, a vibration signal or a combination thereof to know that who is a second caller without looking a caller display. Thereby the user can determine to receive the calling or not from the second caller without looking the caller display.