The codes are checked to most models of Nokia. WARNING NOT ALL codes can go to your phone, but still they are worth.
And just what are they for? The answer is:
1. You can find the serial number
2. Can improve the image quality of the display and sound
3. To determine the firmware version
4. Find out whether to repair your cell
5.Uznat the date of manufacture of your phone
Believe me, this is really useful and inexpensive!