These MOTOROLA codes will work on most Nokia Mobile Phones, however Risay accept no responsibility of any kind for damage done to your phone whilst trying these codes.
 

Code	Description
*#06#	For checking the International Mobile Equipment Identity (IMEI Number).
[][][] 119 [] 1 []	Activate Enhanced Full Rate Codec (EFR) - Your phone uses the best sound quality but talk time is reduced my approx. 5%.
[][][] 119 [] 0 []	Deactivate Enhanced Full Rate Codec (EFR).