Step 1: Update to original iPhone 3.1.3 firmware via iTunes. Download redsn0w 0.9.4 for Windows [Fast Mirror link]
Download redsn0w 0.9.4 for Mac [Fast Mirror link] • Also Download Firmware 3.1.2 (Yes, OS 3.1.2) and save it to your desktop. 2G Users:- iPhone 3.1.2 download 3G Users:- iPhone 3G 3.1.2 download Depending on your PC the above IPSW File may not save as an ipsw file, it may save as a ZIP file, if it does you will need to change the file type so that Redsn0w can locate it. Make sure that you safe the above file in a place on your PC that it will be easy to find it and then watch the video below as this is the easiest way for me to show you how to change the file type: FOR WINDOWS XP: http://www.youtube.com/watch?v=sQFm0Hi35pc FOR WINDOWS 7 AND VISTA: http://www.youtube.com/watch?v=9deovT0nrD4 Step 2: Start redsn0w 0.9.4 and point it to the respective original iPhone 3.1.2 firmware to proceed. Yes you need to point it to iPhone 3.1.2 instead of 3.1.3 because redsn0w 0.9.4 is still unable to validate the latest firmware. Step 3: Now select “Install Cydia”, “Unlock” and “Already pwned” options for iPhone 2G (unlock is not possible on 3G), if you phone has been previously pwned, if your phone has not been previously pwned in the past you can either not put a tick in the ‘Already pwned’ box or you can still tick it but you may be asked for a 3.9 Bootloader and 4.6 Bootloader location which can be downloaded from the links below and stored on your PC 3.9 Bootloader: - http://www.sendspace.com/file/tvmty7 4.6 Bootloader: - http://www.sendspace.com/file/zd4cdy If you have a 3G iPhone then only put a tick in the jailbreak box (install Cydia). Step 4: Now make sure your device is both OFF and PLUGGED IN to the computer before you click “Next”. Step 5: Connect your device in recovery mode by pressing the Power and buttons continuously. At this stage you will be presented with a screen where you will have to quickly hold “Power” button and then while holding the “Power” button, you will now have to hold “Home” button too. Now after few seconds release “Power” button but keep holding “Home” button until installation begins. Step 6: Sit back and enjoy while redsn0w will do all the rest for you. Once done, your iPhone 2G/3G will restart jailbroken running firmware 3.1.3. Unlock for iPhone 2G Only Step 7: Once you are done with the jailbreak, you can now unlock your iPhone 2G running jailbroken firmware 3.1.3 by using BootNeuter app from Cydia. Once you are done with the jailbreak, you can now unlock your iPhone running jailbroken firmware 3.1.2 by using BootNeuter app. Goto Cydia and search for “BootNeuter” app and install this app. Make sure that you have “BigBoss & PlanetiPhones” repository added in Cydia before you make your search for this app. 
Step 8: Now simply restart your iPhone. When BootNeuter starts, set the settings as shown in the screenshot below in order to make sure that phone is unlocked on 3.1.2 firmware. Unlock for iPhone 3G Only | 
