On the main sreen type *#06# for checking the IMEI (international Mobile Equipment identity).
#7780# rest to factory settings.
#67705646# This will clear the LCD display (operator logo).
#0000# To view software version.
#32820# Bluetooth device address.
#764025625# Sim clock allowed status.
#62209526# Display the MAC addressbof the WLAN adapter.
This is avilable only in the newer device that supports WLAN like N80
#92702689# Takes you to a secret menu of the information below. 1. Display Serial Number. 2. Display the Month and Year of Manufacture. 3. DISPLAY (if there) the date where the phone was purchased (MMYY). 4. Display the date of the last repair - if found (0000). 5. Show life timer of phone (time passes since last start).