NOKIA
*#06# :for IMEI
*#92702689# :All Manufacture (Warranty)
*#3370# :Enable EFR (To disable, Type it again. Phone Automatically Restart)
*#0000# :View Software version
*#7780# :Restore factory settings
*#67705646# :Clear LCD Display (Operator Logo)
*#2820# :Bluetooth device address
*#746025625# :SIM lock allowed statue
*#62209526# : Display the MAC address
#pw+1234567890+1# :Show if SIM restrictors.
*#4720# :half rate Codec activation (To disable, Type it again)
*#7370925538# :S-60 (Reset)
Default code is 12345
*#3925538# : Delete the contents and code of wallet
*#7328748263373738# :Reset Phone Code. Default code is 12345
Below are some reset codes for various Series 40, 60 and the new Series 80 Communicator series (Nokia 9300/9500):
Full Reset: (clears everything off the phone memory!! Be sure to back up your contacts!!): *#7370#, 12345 and then Yes.
Soft Reset: *#7780#, 12345 and then Yes. (Also works on Nokia S40 phones as a full reset)
*#335738#
*#delset#
This deletes the Email, GPRS, MMS settings that cannot be erased via phone options. (Newer Series 40 phones only i.e. 6230(b))

SAMSUNG
*#1234# :SW Version
*#2222# :HW Version
*#0842# :Vibrator Test
*#0289# :Buzzer Test
*#0228# :Battery Statue
*#0782# :RTC Display
*#0523# :LCD Contrast
*#0377# :NVM error Log
*#5646# :Logo set
*#0778# :SIM Service Table
*#0638# :SIM Network ID
*#0746# :SIM Info
*#076# : Production no
*#2576# :SIM errors
Lock Manager
*2767*2878# :EPROM Reset
*2767*3855# :Master Reset
*#2767*63342# :Media Reset
*2767*667# :MMS reset
*2767*927# :WAP Reset
If you’re Phone will not reset by using those code:
*2767*637#
*2767*688#
#*7337#
*#9998*3323#
*#9998*627837793#
*2767*7822573738#
unlock Code
Model: Samsung SGH-E715
Turn off the phone. Put a non-accepted SIM Card and turn it on. Type *#9998*3323#. Press Exit. Choose menu #7. After phone reboots type *0141# and hit the Call button. Turn off and insert another SIM Card. Turn on. The code is 00000000.
Model: Samsung SGH-M100
Type *#9998*627837793#. Then type *#9998*737#. Press >/ [] (Play Stop) until phone shows NCK/SPCK number. Press Exit. Type #0111*CODE# (Code is the last 8 digits of the NCK/SPCK)
Model: Samsung SGH-S105
Remove SIM Card. Enter *2767*7822573738# and after phone reboots, enter #0111*00000000#
Model: Samsung SGH-S307
Turn off the phone. Put a non-accepted SIM Card and turn it on. Type *#9998*3323#. Press Exit. Choose menu #7. After phone reboots type *0141# and hit the Call button. Turn off and insert another SIM Card. Turn on. The code is 00000000.
Model: Samsung SGH-X100
Turn off the phone. Put a non-accepted SIM Card and turn it on. Type *#9998*3323#. Press Exit. Choose menu #7. After phone reboots type *0141# and hit the Call button. Turn off and insert another SIM Card. Turn on. The code is 00000000.
Model: Samsung Universal
TEMPORARY UNLOCK:
Put a non-accepted SIM Card and turn it on. Type *#9998*3323#. Press Exit. You will get a new menu. Select Malloc Fail.
In newer phones:
#*7337#