Hello everyone. Good news for all those who were stuck on iPad baseband 6.15.00 on their iPhone 3G or iPhone 3GS. You probably installed the iPad baseband on your iPhone because you restored to a stock IPSW and ended up upgrading your baseband and lost the ultrasn0w-unlockable baseband. Ultrasn0w supports basebands upto 5.13.04 on iPhone 3G and iPhone 3GS. So the iPad baseband trick came to rescue for all those who upgraded their baseband beyond 5.13.04. Installing the iPad baseband 6.15.00 allowed iPhone 3G and iPhone 3GS users to unlock using ultrasn0w, so their iPhones won't just become and iPod!
The iPad baseband method to unlock iPhone 3G and 3GS came to rescue, but with a price. The iPhone with iPad baseband installed had to lose the GPS functionality. The iPhone had to be restored with a custom IPSW, while making sure to select the "install iPad" option. This was not convenient and so now finally the iPhone Dev team has released the method to downgrade the iPhone 3G and iPhone 3GS from iPad baseband to the normal iPhone baseband.
In this tutorial, I will show how to downgrade your iPhone 3G and iPhone 3GS from iPad baseband to iPhone baseband.
Step 1
Download latest redsn0w for Windows or Mac
Download latest iTunes.
The stock IPSW for the iOS your iPhone is currently on. You would probably have it because you used it to create custom IPSW. If you don't have it, then click here to download.
Step 2
Connect your iPhone to your computer.
Open iTunes and sync it (take backup). Close iTunes.
Run redsn0w.
Click Extras, click Select IPSW. Provide the stock IPSW of your iPhone's current iOS version.
Click Back.
Step 3
Power off your iPhone using the Power button.
Click Jailbreak in redsn0w.
When it shows options, select "Downgrade from iPad baseband" option. Uncheck the Install Cydia option if your iPhone is already jailbroken. Otherwise, select it if you would like to jailbreak your iphone.
Step 4
Click Next.
Now you will be guided to enter Pwned DFU mode, so follow the steps shown in redsn0w.
Once your iPhone is in Pwned DFU mode, the downgrade process will start. You will see the Pwnapple logo (running pineapple) and after that, the flashing of baseband will start.
Do not disconnect your iPhone while the process is ongoing. The "Flashing Baseband" process takes about 10 minutes to complete and no progress is shown on screen. So be patient.
When the process is finished, your iPhone will reboot.
Step 5
Check the new baseband.
Go to Settings - General - About and check "Modem Firmware". It should be 5.13.04.
Step 6
Now open Cydia.
Uninstall ultrasn0w and re-install it (or simply upgrade it if you are not on the latest version). Also re-install Mobile Substrate if you are having no signal or your iPhone is crashing.
Step 7
Check the GPS functionality. Open Maps and check the GPS function. It should work fine now.
Okay so that's all. This was the tutorial on how to downgrade iPhone 3G or iPhone 3GS from iPad baseband to iPhone baseband.
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