It is not only me but many people pointed out (Ref, Ref) that after installing Ultrasn0w 1.2.1 update, they were unable to send and receive any SMS on their iPhone. Some people also reported that they were noticing huge battery drain after unlocking their iPhone with Ultrasn0w 1.2.1. I was myself unlocked on iOS 4.2.1 with Ultrasn0w 1.2 and everything was going very smooth until i updated to Ultrasn0w 1.2.1 and started having some severe battery drainage issues on my iPhone 3GS.
This guide is for those iPhone 4/3GS users who are on iOS 4.2.1 or less and want to re-unlock their iPhone using Ultrasn0w 1.2. Using this guide on iOS 4.3.x will not work as all iPhone users on iOS 4.3.x needs to unlock their iPhone with the latest version of Ultrasn0w to fix signal-bars issue.
Steps to Downgrade Ultrasn0w 1.2.1 to Ultrasn0w 1.2 on iOS 4.x.x:
- First you need to uninstall Ultrasn0w 1.2.1. To do that, open Cydia on your jailbroken iPhone and navigate to Manage » Packages section. Scroll down the list of installed packages, tap on Ultrasn0w package and then tap on Modify button on the top-right. Choose Remove option and wait while Cydia uninstalls Ultrasn0w 1.2.1 from your iPhone. Once done, you will be asked to restart the SpringBoard.
- Download Ultrasn0w 1.2 DEB file from the links below:
- Download and install iPhone Explorer from here
- Connect your iPhone to your PC or Mac and launch iPhone Explorer. Once your iPhone has been detected by iPhone Explorer, navigate to the following location and place the Ultrasn0w DEB file in AutoInstall directory.
- Reboot your iPhone. Thats it. Now your iPhone is again unlocked using Ultrasn0w 1.2.