Secret / These for the series of provide some interesting information for users, they also unlock some hidden functions. These are often reffered to as " Secret " or " ". Use the at your own risk, not all support all , I have tried to split them into these groups. These 3 work on 90% of ;

*#06# n/a Display the IMEI (Standard GSM command, works on all ) *#0000# n/a Display the firmware version and date *#92702689# *#war0anty# Here you can view the S/N and the IMEI as well as the life timer (newer models). The date the phone left the factory and the date it was purchased. If your phone has been repaired the date of the repair is also visible. You will need to turn the phone off to exit this menu. Newer simply require you to press ok.
The following are specific to older series 40 ; (Entering the following will restart the phone)

*4720# (*hra0#) Cctivates Half Rate, Half Rate is 5.6kbit/s and uses half the bandwidth at the cost of call quality. Network operators often activate half rate on overloaded towers during pk times to save costs. #4720# (#hra0#) Dctivates Half Rate *3370# (*efr0#) Activates Enhanced Full Rate, EFT attempts to match wire quality. The calls are 12.2kbit/s and are not supported by all operators. It is compatibale with the hightest AMR mode. #3370# (#efr0#) Dctivates Enhanced Full Rate *#746085685# (*#sim0clock#) Display the SIM clock status
The following are phone specific or phase related;

*#7220# (*#pca0#) Activate the GPRS PCCCH support (Packet Common Control Channel) *#7230# (*#p0#) Dctivate the GPRS PCCCH support *#7760# (*#ssn0#) Display the manufacturing
This only works on the 3310 and 3330;

*#67705646# (*#opr0logo#) Clr the operator logo, the logo will be reset to the default network operator logo.
The following work on newer series 40 & series 60/80 ;

*#2820# (*#bta0#) Display the Bluetooth MAC address (Phone must have a built in bluetooth adapter) *#7370925538# (*#res0wallet#) Reset the mobile wallet (Phone must have the mobile wallet fture) *#7370# (*#res0#) Soft-format the memory (Symbian) *#7780# (*#rst0#) Reset to factory defaults, confirmation required (also known has a Hard-format), all phone contents will be wiped cln including contacts and smses if they are stored on the phone If you have any other or tips plse do not hesitate to forward them to me and I will add them here.