iPhone | How to Jailbreak and Unlock Your iPhone 3GS Using RedSn0w (Windows) [4.2

NOTES:
If you have problems with RedSn0w on Windows Vista or Windows 7.
Right click the executable and set it to run as administrator in
Windows XP compatibility mode.

IMPORTANT:
If you have a newer iPhone 3GS and performed a tethered jailbreak you
can use Redsn0w to help you boot back into your jailbroken device.
Simply select Just boot tethered right now from the options window and click Next.
[You must be registered and logged in to see this link.]

UNLOCK:
Follow [You must be registered and logged in to see this link.] tutorial to unlock your device if you updated to the 06.15.00 baseband.


*As usual a big thanks to the iPhone Dev-Team for their hard work and contribution to the iPhone community.

Step Eight
From this window you can select the jailbreak options you would like.
[You must be registered and logged in to see this link.]

Verbose boot displays detailed information on boot of your device and is generally only needed by developers and advanced users.

Make sure Cydia is selected. For this tutorial we will also select Custom boot logo and Custom recovery logo.

When you click to select each custom logo option a dialog window will
appear asking you to select the image. Locate the image you would like
to use then press the Open button.
[You must be registered and logged in to see this link.]

*Remember the rules for boot logos are: RGB or Grayscale format with
Alpha channel and dimension below 320x480. If you would like to use
the iClarified ones they can be found here: [You must be registered and logged in to see this link.], [You must be registered and logged in to see this link.]

If you read the warning above and you would like to update your baseband to the 06.15 iPad version for unlock then check Install iPad Baseband. Click Yes when prompted to confirm your decision.
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Click the Next button continue.
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Step Nine
Please plug your iPhone into the computer and make sure its OFF then click the Next button
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Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode [You must be registered and logged in to see this link.]

Hold down both the Home button and the Power button for 10 seconds.
[You must be registered and logged in to see this link.]

Release the Power button and continue holding the Home button until RedSn0w detects the device.
[You must be registered and logged in to see this link.]

Step Eleven
RedSn0w will now download the iPad baseband if needed and your iPhone will reboot
[You must be registered and logged in to see this link.]

Step Twelve
RedSn0w will then begin uploading the new RAM Disk and Kernel.
[You must be registered and logged in to see this link.]

Step Thirteen
Once this is complete you will be notified that RedSn0w is done. Click the Finish button. When your iPhone finishes rebooting (5 minutes or so) it will be jailbroken with Cydia on the SpringBoard.
[You must be registered and logged in to see this link.]

These are instructions on how to jailbreak your iPhone 3GS on the 4.2.1
firmware using RedSn0w for Windows. The Mac version of this tutorial
is [You must be registered and logged in to see this link.].

If you have an iPhone 3GS with the new bootrom you will only be able to perform a [You must be registered and logged in to see this link.] jailbreak at this time. This means you will need Redsn0w's assistance to boot into your jailbroken device.

IMPORTANT FOR UNLOCKERS
During this process you can update your baseband to the 06.15 version.
If you are on 05.14 or 05.15 or higher you will need to do this to
unlock. You do not need to do this for jailbreak only. Please read the
following very carefully before deciding whether to do this. You can
find out baseband version [You must be registered and logged in to see this link.].

1. There is no way to come back down from 06.15, and there’s no hiding
the baseband version from Apple. You’ll be voiding your warranty in a
very obvious way.
2. If some future baseband comes out with a critical fix, you won’t be
able to update to it if it remains down in the 05.xx sequence (then
again, you wouldn’t update to it if you wanted to keep your unlock
anyway).
3. Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t
ever be able to restore to stock firmware (it will fail). You’ll need
to only restore to custom IPSWs (then again, if you’re unlocker you
should already be doing that).
4. There are reports that 06.15 [You must be registered and logged in to see this link.] disable your GPS. The iPhone Dev-Team is currently working on a fix.

Don’t update to 06.15 if you don’t need to! Only do this if you need
the unlock and you’re stuck on 05.14 or 05.15, and you’re willing to
assume the above risks.


Step One
Create a folder on your desktop called Pwnage

Download RedSn0w from [You must be registered and logged in to see this link.] and place it in the Pwnage folder. Likewise, download the latest 4.2.1 firmware from below and place it in the same folder.

4.2.1 (3GS): [You must be registered and logged in to see this link.]

Extract the redsn0w executable from the RedSn0w zip file into the same folder.
[You must be registered and logged in to see this link.]

Step Two
***If you are already on iOS 4.2.1 you can skip this step. If you are
on an unlockable baseband and on a lower firmware you should use
PwnageTool instead to update [You must be registered and logged in to see this link.] your baseband.

Connect your iPhone to the computer and launch iTunes.
[You must be registered and logged in to see this link.]

Select your iPhone from the list of devices on the left. Now hold down Shift and click the Restore button. Restore is preferred as it won't create any wasted space on your iPhone.
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Navigate to the Pwnage folder on your desktop and select the 4.2.1 firmware ipsw. Click the Choose button to continue.
[You must be registered and logged in to see this link.]

Step Three
Once iTunes has finished updating your iPhone to the desired firmware open the Pwnage folder on your desktop and launch the redsn0w application from the redsn0w folder we extracted earlier.
[You must be registered and logged in to see this link.]

Step Four
Once RedSn0w opens click the Browse button
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Step Five
Select the 4.2.1 firmware ipsw we placed in the Pwnage folder on our desktop then click Open.
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You will be asked if this device is a newer fixed model. If yours is
then click the Yes button; otherwise, click the No button. At this time
you can only perform an untethered jailbreak on the older model.
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Step Six
Once the firmware has been verified click the Next button to continue.
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Step Seven
RedSn0w will now prepare the jailbreak data
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