This is my first Android app, so don't be too harsh
It is published on android market, search for 'Call Control'.
Call Control periodically generates sound beeps, which are heard only on your side, during phone calls.
While active, this program makes a beep sound at the predefined time mark during the phone call.
Use Call Control to make yourself conscious of time spent on phone during call.
Call Control works automatically after install.
It comes in handy if you don't have lot of minutes left.
Main app screen where you can switch notifications on/off.
Select different alert tone:
Select notification interval: