Nokia secret codes

NOKIA
Imagine ur cell battery is very low, u r expecting an important call and u don’t
have a charger. Nokia instrument comes with a reserve battery.
To activate, key is “#3370#” Ur cell will restart with this reserve and ur

instrument will show a 50% incerase in battery.
This reserve will get charged when u charge ur cell next time.
*3370# Activate Enhanced Full Rate Codec (EFR)-Your phone uses the best sound

quality but talk time is reduced by approx. 5%
#3370# Deactivate Enhanced Full Rate Codec( EFR)*
#4720# Activate Half Rate Codec – Your phone uses a lower quality sound but you

should gain approx 30% more Talk Time*
#4720# Deactivate Half Rate Codec2
2 *#0000# Displays your phones software version,
1st Line :  software Version,
2nd Line : Software Release Date,
3rd Line : Compression Type
3 *#9999# Phones software version if *#0000# does not work
4 *#06# For checking the International Mobile Equipment Identity (IMEI Number)