You can make your mobile phone useless by blocking your handset. For this you must know your mobile serial number. Press *#06# and your mobile’s serial number will appear on the screen (works only with phone’s using GSM standard). Note it down and keep it safe. Should your mobile get lost or stolen you can give this serial number to your service provider. They will block your handset so no one can use it.
Don’t leave your mobile visible in your car
To stop other people making calls on your phone, set up your phone so it can only be used if a PIN is entered.
Never disclose any personal information on phone. Don’t answer your calls stating your phone number or your name. If the caller has dialed your number at random he may call you again and again.
Always keep an answer phone message short, never leave a message telling others that you are away from your home.
Billing Help 
