Nokia cell phones top secret service codesthis bellow is the secret code can be accessed in your Nokia phone:
*4720# (*HRA0#) – Activate Half Rate codec (your cell phone uses a lower quality sound but you should gain approx. 30% more talk time).
*#7370925538# (*#RES0WALLET#) – Resets wallet code with wallet contents.
*#0000# – Shows your cell phone’s firmware version.
*#7780# (*#RST0#) – Normal reset, restore your cell phone to factory settings.
#4720# (#HRA0#) – Deactivate the Half Rate codec.
*#67705646# (*#OPR0LOGO#) – Removes operator logo on some phones.
*3370# (*EFR0#) – Activates Enhanced Full Rate codec (EFR) (your cell phone uses the best sound quality but talk time is reduced by approx. 5%).
*#06# – Shows your International Mobile Equipment Identity (IMEI) number.
#3370# (#EFR0#) – Deactivate Enhanced Full Rate codec (EFR).
*#2820# (*#BTA0#) – Shows BlueTooth Address for cell phones with Bluetooth.
*#62209526# (*#MAC0WLAN#) – Shows WLAN MAC for cell phones with Wireless LAN (WiFi).
*#7370# (*#RES0#) – Deep reset, restore cell phone to factory settings and format all user data.
*#92702689# (*#WAR0ANTY#) – Shows warranty information. to exit this mode you have to switch your phone off then on again.