If you have accidently locked your iPhone 3GS/3G and looking for a way to downgrade your iPhone 3GS/3G baseband so that you can unlock it again, then this might be helpful as Musclenerd has released the Redsn0w 0.9.14b1 which is capable to downgrade your iPhone 3GS/3G 06.15.00 baseband to 05.13.04 baseband which can be unlocked using the Ultrasn0w. This Redsn0w 0.9.14b1 can also fix the GPS, and the stock firmware issues due to iPad baseband once you successfully downgraded it.

Things you need to know ??

• This Downgrading method will work only for iPhone 3GS/3G  with the iPad baseband 06.15.00 and is not applicable to the other iDevices like iPhone 4 and iPhone 4S.
• After Downgrading with Redsn0w, your iPhone 3GS/3G will have a baseband 05.13.04, no matters whether you are on this baseband previously or not.

Now, let’s see how you can downgrade iPhone 3GS / 3G baseband 06.15.00 to baseband 05.13.04 to fix GPS and unlock with UltraSn0w.

How to Downgrade iPhone 3GS / 3G 06.15.00 To 05.13.04 Baseband

Download RedSn0w and the firmware that your iPhone 3GS or iPhone 3G is currently running:

• Download the version of your iOS which your iPhone is currently running. Also,
• Download RedSn0w 0.9.14  from these links :-
• (For Mac)  | (For Windows)

Step 2

Now you need to extract the Redsn0w .Zip file with Winzip/Wirar or 7-zip on your Desktop for simplicity. Once thing you need to keep in mind if working on Windows.

• Run the Extracted Redsn0w Program in Administrator Mode on Windows.

And then Click on the Extras and then Browse IPSW,  and select the downloaded iOS firmware (ipsw) file and open it.

Step 3 : Click Ok to confirm your selection and then RedSn0w will ask for a newer or older model iPhone 3GS. If you’ve an iPhone 3GS New Bootrom, click Yes. For an old Bootrom iPhone 3GS , click No.

Step 4: Now click Back button to go back to RedSn0w’s main menu and click on the Jailbreak button and wait.

Step 5 : Now Select or check the option where it says “Downgrade from iPad baseband” checkbox, RedSn0w will present you with a warning read it carefully and click Yes. Disable Cydia (if you already have it installed), and click Next.

Step 6 : Plug your iPhone 3GS or 3G to your computer and make sure it’s OFF. Do a controlled shutdown of your iPhone (“slide to power off”).  This step is very important to avoid mounting problems when the ramdisk is running!  Now click Next.

Step 7 : Put your iPhone into DFU mode. Follow the on-screen instruction to put your iPhone into DFU mode.

• Release the Power (corner) button for 3 seconds
• Without releasing the Power button, also hold down the Home button for 10 seconds
• Without releasing the Home button, release the Power button BUT keep holding the Home button until RedSn0w detects the device.

Step 8 : Now once you entered the DFU mode, RedSn0w will immediately begin jailbreaking process on your iDevice. All you need to do is to sit back and relax for a few minutes as it requires some time depending on your Computer’s speed.

Step 9 : Once the jailbreak process is completed, Follow the On-Screen instructions given by redsn0w as nothing new is there to teach you now.

Step 10 : Now you will see the Pwnapple running on your iPhone, you’ll eventually get to the “Flashing Baseband” option on your screen. THIS STEP TAKES A VERY LONG TIME to complete and there won’t be any feedback while its running.  Please just let it be for the next 3-8 minutes!  When the ramdisk has done its job it will reboot the phone on its own.

After the reboot, your iPhone 3GS will be running 05.13.04 baseband. You can unlock your iPhone 3GS/3G, Open Cydia, let it update, search for UltraSn0w and install it.

That’s it! You are done ! If you have any problems in following the steps, then ask for help in the comments.