[Guide] How to downgrade iPhone 06.15 baseband using Redsn0w

Users who upgraded their iPhone 3G or iPhone 3GS past the 05.13.04 basebands found themselves having to use the iPad’s 06.15 baseband in order to enjoy their unlocked status. But thanks to the iPhone Dev Team, you can now downgrade your baseband to 05.13.04 using Redsn0w so you can enjoy Ultrasn0w compatibility, full GPS and the ability to use stock IPSW files.

Check out our following guide on how to downgrade iPhone 06.15 baseband using Redsn0w.



NOTE Please backup your iPhone data before you proceed. We will not be responsible for any loss of data or device malfunction which may occur from improper use of this guide, so please continue at your own risk.

1. Download Redsn0w 0.9.14b1 ( WINDOWS | MAC OS )
2. Run Redsn0w (use admin mode in Windows)
   
   • Click Extras
   • Click ‘Select IPSW’
   • Point Redsn0w to the firmware you have currently installed on your device.
3. Turn off your device
4. On Redsn0w click ‘< Back’ to return to the homescreen
   
   • Click ‘Jailbreak’
   • Enable the ‘Downgrade from iPad baseband’ checkbox.
   • Disable Cydia if you already have it installed
   • Click Next and proceed to set your device in DFU mode.
5. The process of flashing the baseband can take several minutes so be patient until it is completed and the phone reboots.

NOTE If you’re still using ultrasn0w after going down to 05.13.04, many people have reported that re-installing Mobile Substrate and/or ultrasn0w fixes crashes and “No Signal”.

iPhone Dev Team -

“ 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! “