How to Downgrade Your iPhone 3GS, 3G Baseband for Unlock (Windows)

These are instructions on how to downgrade your iPhone 3GS or iPhone 3G’s baseband from the iPad’s 06.15 baseband to 05.13.04 using RedSn0w for Windows. The Mac version of this tutorial can be found here.

Typically you’d have the 06.15 baseband if you unlock with ultrasn0w but updated your iPhone baseband past 05.13.04. With this new capability, you can now downgrade specifically from 06.15 to 05.13.04 (even if you never had 05.13.04 on that device before). This gives you the best of both worlds: ultrasn0w unlock compatibility and a normal iPhone baseband with full GPS and the ability to use stock IPSWs again.

Step One
Create a new folder on your desktop called Pwnage.

In the folder place the current firmware of your device (which can be downloaded from here) and the latest version of RedSn0w (from here).

Extract the RedSn0w zip file by double clicking it.

Step Two
Launch the redsn0w application from the redsn0w folder we extracted earlier. You can do this by right clicking the executable and selecting Run as Administrator contextual menu.

Step Three
Once RedSn0w opens click the Extras button.

Step Four
Choose Select IPSW from the Extras menu.

Step Five
Navigate to the Pwnage folder on your desktop, choose the firmware ipsw we downloaded earlier, and click Open.

Click OK to confirm your selection.

Tell RedSn0w whether you have a newer or older model iPhone 3GS.

Step Six
Press Back to get back to the main menu then click the Jailbreak button.

Step Seven
RedSn0w will now prepare the jailbreak data.

Step Eight
Check the Downgrade from iPad baseband checkbox, uncheck Cydia if you already have it installed, and click Next to proceed through the normal DFU ramdisk steps.

Step Nine
Plug your iPhone into the computer and make sure its OFF then click the Next button

Step Ten
RedSn0w will now guide you through the steps to get into DFU mode. You can find more help with DFU mode here.

Hold down both the Home button and the Power button for 10 seconds.

Release the Power button and continue holding the Home button until RedSn0w detects the device.

Step Eleven
Your iPhone will now be exploited with limera1n and reboot

Step Twelve
Your iPhone will now be rebooted again and RedSn0w will begin uploading the new RAM Disk and Kernel.

Step Thirteen
RedSn0w will now inform you that its work is done. The rest of this process will take place on your device.

Step Fourteen
After showing some scrolling text, your iPhone will display the pwnapple icon and say Flashing Baseband. 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.

Step Fifteen
Once the phone has rebooted you will be on the 05.13.04 baseband.

***A big thanks to the iPhone Dev-Team for making this possible!

iPhone Dev-Team Announces Baseband Downgrade for iPhone 3GS, 3G [Released]

The iPhone Dev-Team has announced a baseband downgrade from the iPad’s 06.15 baseband on the iPhone 3GS and iPhone 3G.

Typically you’d have the 06.15 baseband if you unlock with ultrasn0w but updated your iPhone baseband past 05.13.04. With this new capability, you can now downgrade specifically from 06.15 to 05.13.04 (even if you never had 05.13.04 on that device before). This gives you the best of both worlds: ultrasn0w compatibility and a normal iPhone baseband with full GPS and the ability to use stock IPSWs again.

Steps:
1. Use the “Extras->Select IPSW” button in redsn0w to tell it which firmware version you have installed (new-bootrom 3GS users can usually skip this step but it doesn’t hurt for them to do it too).
2. Do a controlled shutdown of your iPhone (“slide to power off”). This step is very important to avoid mount problems when the ramdisk is running!
3. Go back to the first screen and click “Jailbreak”. Enable the “Downgrade from iPad baseband” checkbox, disable Cydia if you already have it installed, and click Next proceed through the normal DFU ramdisk steps.

Note: The “Flashing Baseband” step TAKES A VERY LONG TIME to complete (3-8 minutes).

For those who are wondering if you can update your 3G or 3GS to 06.15 solely for the purposes of downgrading to 05.13.04, the answer is “yes” for 3G owners, and “maybe” for 3GS owners. The iPad baseband is not compatible with 3GS units manufactured week 34 of 2011 or later. If you have an iPhone3GS and if digits 3-5 of its Serial Number are 134 or later (xx134…), then you should NOT try to install the 06.15 baseband on your 3GS! It will brick your radio, preventing both the downgrade from working and normal iPhone software from using it as a phone! Be warned!

 
Read More