This is a very useful info provided if u r a mobile savvy...
Some info in case u have a Nokia...
1) 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 Codec
2) *#0000# Displays your phones software version,
1st Line :S oftware Version,
2nd Line : Software Release Date,
3rd Line : Compression Type
3) *#9999# Phones software v ersion if *#0000# does not work
4) *#06# For checking the International Mobile Equipment Identity (IMEI
Number)
5) #pw+1234567890+1# Provider Lock Status. (use the "*" button to obtain
the "p,w" and "+" symbols)
6) #pw+1234567890+2# Network Lock Status. (use the "*" button to obtain
the
"p,w" and "+" symbols)
7) #pw+1234567890+3# Country Lock Status. (use the "*" button to obtain
the
"p,w" and "+" symbols)
8) #pw+1234567890+4# SIM Card Lock Status.(use the "*" button to obtain
the
"p,w" and "+" symbols)
9) *#147# (vodafone) this lets you know who called you last *#1471# Last
call (Only vodofone)
10) *#21# Allows you to check the number that "All Calls" are diverted
To
11) *#2640# Displays security code in use
12) *#30# Lets you see the private number
13) *#43# Allows you to check the "Call Waiting" status of your phone.
14) *#61# Allows you to check the number that "On No Reply" calls are
diverted to
15) *#62#...