There's a lot of secret code for android phone which we don't know. By using this code, you can change the settings of your Android phone. Let's look.

*#06# = IMEI number will be displayed.

*2767*3855# = Reset Phone factory.

*#*#4636#*#* = Phone and Battery information.

*#*#273282*255*663282*#*#* = All media file back-up code.

*#*#197328640#*#* = Service setting reset code.

*#*#1111#*#* = FTA software version.

*#*#1234#*#* = PDA and firmware version.

*#*#232339#*#* = Wireless LAN test code.

*#*#0842#*#* = Backlight and vibration test code.

*#12580*369# = Software and Hardware information. 

*#*#2664#*#* = Touch screen test code. 
*#9900# = System Dump Mode. 

*#9090# = Diagnostic Configuration.

*#*#34971539#*#* = Camera Information.

*#872564# = USB Login Control.

*#301279# = HSDPA/HSUPA Control Menu.

*#7465625# = Phone lock status.

*#*#7780#*#* = Factory restore settings. The system will delete all data.

*2767*3855# = Factory format setting. All internal and external data can be deleted and firmware will be re-installed.

*#*#273283*255*663282*#*#*= File copy screen. All image, sound, video, voice memo can be backed up.

*#*#197328640#*#* = Service mode code. Different test and setting can be changed.

*#*#7594#*#* = Your end-call/power-button is becoming a direct power off button.

*#*#8255#*#* = G-talk service monitor code.

*#*#34971539#*#* = Camera information. The camera firmware update version do not use, because it will be closed of your camera function.
 

W-LAN, GPS and Bluetooth Test Codes:

*#*#232339#*#* OR *#*#526#*#* OR *#*#528#*#*= W-LAN test code. Use the menu button to start test.

*#*#232338#*#* = WiFi Mac Address.

*#*#1472365#*#* = GPS Test.

*#*#1575#*#* = Another GPS Test Code.

*#*#232331#*#* = Bluetooth Test Code.

*#*#232337#*# = Bluetooth devices information.

*#*#0588#*#* = Proximity Sensor Test.

*#*#0*#*#* = LCD Test.

*#*#2663#*#* = Touch Screen Version.

*#*#0283#*#* = Packet Loop Back.

*#*#0673#*#* OR *#*#0289#*#* = Melody Test.

*#*#3264#*#* = RAM Version Test.