Below are some hidden engineer codes for Nokia phones. Not all of them will work on every phone, and you use them at your own risk! That said, you should be able to find some interesting information about your phone...

*3370# - Activate Reserve Battery

*#4720# - Activate Half Rate Codec - Your phone uses a lower quality sound but you should gain approx 30% more Talk Time

*#0000# - Display software version as below:

1st Line - Software Version,
2nd Line - Software Release Date,
3rd Line - Compression Type

*#9999# - Display software version (where above doesn't work)

*#06# - Display IMEI Number

#pw+1234567890+1# - Provider Lock Status (use the "*" button to obtain the p, w and + symbols)

#pw+1234567890+2# - Network Lock Status

#pw+1234567890+3# - Country Lock Status

#pw+1234567890+4# - SIM Card Lock Status

*#21# - Check the number that "All Calls" are diverted to

*#2640# - Display security code in use

*#43# - Check the "Call Waiting" status of your phone.

*#61# - Check the number that "On No Reply" calls are diverted to

*#62# - Check the number that "Divert If Unreachable" calls are diverted to

*#67# - Check the number that "On Busy Calls" are diverted to

*#73# - Reset phone timers and game scores

*#746025625# - Display SIM Clock status

*#7760# - Manufacturer code

*#7780# - Restore factory settings

*#92702689# - Displays:

1.Serial Number
2.Date Made
3.Purchase Date
4.Date of last repair (0000 for no repairs)
5.Transfer User Data

To exit this last screen, you need to switch your phone off then on again.