Now a days as you all know great smartphones are coming with the Google best OS known as Android.
This codes are successfully tested by me on my latest Samsung galaxy Android 2.2. Note- Do not usually play with these codes because sometime it may destruct your phone also.


1. Complete Information About your Phone 

*#*#4636#*#*

Displays-

• Phone information
• Battery information
• Battery history
• Usage statistics 

2. Factory data reset

*#*#7780#*#*

Displays-

• Google account settings stored in your phone
• System and application data and settings
• Downloaded applications

It'll not remove:

• Current system software and bundled application
• SD card files e.g. photos, music files, etc.

3. Format Android Phone

*2767*3855#

It'll remove all files and settings including the internal memory storage. It'll also reinstall the phone firmware.
Note: Once you give this code, there is no way to cancel the operation unless you remove the battery from the phone. So think it twice before giving this code above.

4. Phone Camera Update

*#*#34971539#*#*

It shows following 4 menus such as:

• Update camera firmware in image (Don't try this option)
• Update camera firmware in SD card
• Get camera firmware version
• Get firmware update count

5. File Copy for Creating Backup

*#*#273283*255*663282*#*#*

This code opens a File copy screen where you can backup your media files e.g. Images, Sound, Video and Voice memo.

6.  Service Mode

*#*#197328640#*#*

This code can be used to enter into Service mode. You can run various tests and change settings in the service mode.

7. WLAN, GPS and Bluetooth Test Codes:

*#*#232339#*#* OR *#*#526#*#* OR *#*#528#*#* - WLAN test (Use "Menu" button to start various tests…)
*#*#232338#*#*                  - Shows Wi-Fi MAC address
*#*#1472365#*#*                - GPS test
*#*#232331#*#*                  - Bluetooth test
*#*#232337#*#                    - Shows Bluetooth device address

8. Codes to get Firmware version information:

*#*#4986*2650468#*#* - PDA, Phone, H/W, RFCallDate
*#*#1234#*#* - PDA and Phone
*#*#1111#*#* - FTA SW Version
*#*#2222#*#* - FTA HW Version
*#*#44336#*#* - PDA, Phone, CSC, Build Time, Change list number

9. Codes to launch various Factory Tests:

*#*#0*#*#* - LCD test
*#*#0842#*#* - Device test (Vibration test and Backlight test)
*#*#2663#*#* - Touch screen version
*#*#2664#*#* - Touch screen test
*#*#0588#*#* - Proximity sensor test
*#*#3264#*#* - RAM version