Nokia Mobile hidden Codes list to do all the secret things

On the main screen on your Nokia Made mobile phone type in:
*#06# for checking the IMEI (International Mobile Equipment Identity).
*#7780# reset to factory settings.
*#67705646# This will clear the LCD display(operator logo).
*#0000# To view software version.
*#2820# To show Bluetooth device address.
*#746025625# Sim clock allowed status.
#pw+1234567890+1# Shows if sim have restrictions.
*#92702689# takes you to a secret menu where you may find some of the information below:
1. Displays Serial Number.
2. Displays the Month and Year of Manufacture
3. Displays (if there) the date where the phone was purchased (MMYY)
4. Displays the date of the last repair – if found (0000)
5. Shows life timer of phone (time passes since last start)
*#3370# Enhanced Full Rate Codec (EFR) activation. Increase signal strength, better signal reception. It also help if u want to use GPRS and the service is not responding or too slow. Phone battery will drain faster though.
*#3370* (EFR) deactivation. Phone will automatically restart. Increase battery life by 30% because phone receives less signal from network.
*#4720# Half Rate Codec activation.
*#4720* Half Rate Codec deactivation. The phone will automatically restart