How to Jailbreak iPhone 3GS on OS 3.1( Windows)

First:
Download iPhone 3GS 3.1 Custom Firmware : Google is your F.R.I.E.N.D
Please do not ask links to custom IPSWs in your comments, because the software in them is copyrighted by Apple. For legal issues we can’t link you for modified custom firmware.

Download the custom firmware and place to your desktop. These custom firmware are Jailbreaked and contains Cydia for using the full potential of jailbreaking.

Put your iPhone in Recovery mode by following instructions.

Turn the device completely off and disconnect it from cable/dock.

Hold down the home button.

While holding down the home button connect to a computer with a cable (easiest) or dock.

Keep holding down the home button until you see a connect-to-iTunes screen You are now in recovery mode.

Launch iTunes, hold the shift key and then hit Restore button. For Mac hold Option key on your Mac and then hit the restore button. Make sure to hit the restore button.In the dialog box that pops up, browse the downloaded custom firmware file and let iTunes do it’s job. Once the upgrade is finished you haven’t need to jailbreak it again since it was already jailbroken

First:

Download iPhone 3GS 3.1 Custom Firmware : Google is your F.R.I.E.N.D

Please do not ask links to custom IPSWs in your comments, because the software in them is copyrighted by Apple. For legal issues we can’t link you for modified custom firmware.

Step 1: Preparing your iTunes

Launch your iTunes9.x (upgrade to latest), connect your iPhone and sync to backup all your data.

Once download of the required .ipsw file completes, Move it to the following location:

Windows 7:
“C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates\”

Vista
“C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates\”

XP
“C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPhone Software Update\”

Now, Re-open iTunes, you will be prompted to install the new firmware 3.1, DO NOT UPDATE from this prompt. Just close this dialog.

Step 2: Restoring

Now, lets restore the 3.1 custom Firmware. To do this, press and hold left “Shift” button on the keyboard and then click on “Restore” (Not “Update”) button in the iTunes and then release the “Shift” button.

New window popsup asking you to locate your custom firmware. After selecting, iTunes will start decompressing and then will install. This is an automatic process, sit back and relax.

When it finishes your iPhone 3GS is unlocked and Fully Jailbroken.

Step 3: Syncing (optional)

Once you are done with the unlocking and jailbreak process. You can now restore all your settings, apps, music, contacts and photos to the newly installed firmware version 3.1 by restoring the backup that you made in Step 1 from iTunes.

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