There are a number of “secret” codes that can be entered on Symbian phones in particular the Nokia 5230, if your phone asks for the unlock code at any point the default value is 12345.
Shows your software and firmware version, including information such as Software version, Software version date, Custom version, Custom version date, Language set, Model, Type and Latest update
|*#06#||IMEI (International Mobile Equipment Identity) Number|
Shows your IMEI number, each mobile phones number is unique
|*#7780#||Soft Reset Code|
Restores the default factory settings without affecting your contacts, messages, files, etc
|*#7370#||Hard Reset Code|
Will erase all data, including contacts, messages, files, etc. on the phone returning it back to its default factory settings. It is best practice to backup your settings and removing your memory card before using this option
|*#2820#||Bluetooth Device Address|
Shows the devices Bluetooth device address for manually connecting to a Bluetooth device (Note that Bluetooth must be turned on before entering this code)
Shows the total outgoing call minutes since the last hard reset.