Jailbreak n Unlock iOS 3.1.3

• Download iReb 4.0.x-4.1
• Turn off iphone. Now connect it to laptop (in powered off state)
• Put iphone into DFU mode. (use the HOW TO DFU mode video rom YouTube to match the 10 sec timing)
 

•  Run iReb and select iphone 3G among the models.
•    - iphone will turn white screen and then green screen.
• Start iTunes now. it will ask to restor the iPhone in DFU mode.
•   - press SHIFT+RESTORE and browse 3.1.3 ipsw.
•   - Now itunes will retsor the iphone
• PS- in restore process if an error 1611 occurs, just plug out iphone from usb and connec to a different usb of laptop
• and start from step3 onwards.