How many times have you rung a client and did not get through?  Or you had to ring back in 30 minutes. Quite often you forget to ring back. It's so easy to forget as you have already dealt with the situation and it is very difficult to re-introduce an action.
This project is a call reminder. Just push the button and each time a LED will illuminate to represent 10 minutes. It's a count-down timer and after the preset time has elapsed, the piezo will beep.