There are some useful secret codes for Nokia S60′s phones to get system information, such as IMEI and software version. To enter theses codes, the phone must be in the idle screen (not in the menu screen). What is idle screen? This is the screen where you see the operator name, date, time, battery level, signal strength and some other stuff. You can switch between idle screen and menu screen using Menu key ().
*#0000# – Display the software version, the date when the software was built and the phone model. In some cases, the phone model is not the one used by marketing. It is the internal model used inside Nokia. For example, RM-36 is the internal name of Nokia 6680.
*#06# – Display IMEI (International Mobile Equipment Identify) of your phone.
*#2820# (*#BTA0#) – Display the Bluetooth device address of your phone.
*#62209526# (*#MAC0WLAN) – Display the MAC address of the WLAN adapter. This is available only in the newer devices that support WLAN
*#7370# (*#RES0#)- Reset your phone to the default factory settings. Usually you will need this code when you want to reset your phone back to the same condition when you got it for the first time. When the phone ask for security code, the default one is 12345.
Warning: Before you do reset the phone, make sure that you don’t have important data. Your data on the phone memory will be lost once you reset it.
Update (11-Aug-06): I have added some more secret codes at this new posting.