nokia secret codes
*3370# >> It activates Enhanced Full Rate Codec (EFR).
#3370# >> Deactivate Enhanced Full Rate Codec (EFR).
*#9999# >> check nokia phone software version if *#0000# does not work
*#2640# >> Displays the current phone security code.
*#30# >> Lets you see the private number.
*#06# >> For checking the International Mobile Equipment Identity in short imei no.
press and hold # >> switch between lines 1 and 2.
*#7780# >> Restore factory settings