Jailbreak and unlock iOS 4.2.1 with redsn0w 0.9.6b5
Redsn0w 0.9.6b5 jailbreaks iOS 4.2.1 but also provides the added ability to install baseband firmware that can be unlocked for the iPhone 3GS and iPhone 3G. For other iOS devices, redsn0w 0.9.6b5 will simply jailbreak the device but some models will be a tethered jailbreak.
It’s very important to remember that the 06.15 baseband update for iPhone 3GS and iPhone 3G that is required for an update is irreversible and it will void your iPhone warranty with Apple. This is currently the only way to unlock 05.14 and 05.15 basebands. Proceed at your own risk.
How to Jailbreak and Unlock iPhone 3GS and iPhone 3G with iOS 4.2.1 and Redsn0w 0.9.6b5
If you are wondering how to use redsn0w to jailbreak and unlock, you are at the right guide. This is a two stage process, first you jailbreak your iPhone with redsn0w and update the baseband, and then you unlock the iPhone 3GS or iPhone 3G with ultrasn0w 1.2 unlock.
- Download redsn0w 0.9.6b5 or download redsn0w 0.9.6b6 for Mac or Windows
- Download iOS 4.2.1 IPSW that corresponds with the hardware that you want jailbroken
- After you have downloaded redsn0w and the IPSW file, launch redsn0w 0.9.6b5 (Windows users must run redsn0w as Administrator in XP Compatibility Mode)
- Click on “Browse”
- Select the IPSW file you downloaded that corresponds to your iOS device
- Jailbreak only: In the next screen, select that you want to install Cydia
- Unlock & Jailbreak: Select that you want to install Cydia, and also select that you want to install iPad baseband (this works with iPhone 3GS and iPhone 3G)
- If you have selected the iPad baseband, you will see a warning screen asking you to verify that you want to install the baseband update – this voids your warranty and you will not be able to downgrade or revert this update
- Click “Yes” if you want to unlock and understand the ramifications of losing your warranty and permanently updating the baseband
- Now follow the instructions in redsn0w to jailbreak and unlock the iPhone, turn it off then connect the iPhone to your computer and click “next”
- Following the directions, put your iPhone into DFU mode by holding the Home and Power buttons together for 10 seconds, then release the power button and just hold onto the Home button for an additional 3 seconds
- The iPhone screen may flash
- Click on “Finish” and the device will be jailbroken, if you chose to install the 06.15 baseband this will be installed too
- NOTE: It’s a good idea to reboot your iPhone manually before trying to use Cydia
Now that the iPhone is jailbroken, you need to unlock the iPhone with ultrasn0w 1.2:
- Once your iPhone has been rebooted, launch the newly installed Cydia
- Tap “Manage” and then tap “Sources”
- Tap on “Edit”
- Tap on “Add” then enter the following URL for a repository: http://repo666.ultrasn0w.com
- Then tap “Add Source”
- Cydia will now update its sources
- Search for “ultrasn0w 1.2″ within Cydia
- Download and install ultrasn0w 1.2 and then restart your iPhone, this will unlock your iPhone 3GS and iPhone 3G
- Enjoy your unlocked iPhone
If you followed the guide correctly, you will now have an unlocked iPhone and you will be able to use it on other carriers. Devices that can not be unlocked will simply be jailbroken, some of which may be tethered. You can read the difference between tethered jailbreak vs untethered jailbreak, but essentially a tethered jailbreak requires you to connect your iPhone to boot the jailbroken device and use things like Cydia and Safari.
For Windows 7 and Vista users, be sure to run redsn0w as Administrator in “Windows XP Compatability Mode” if you encounter any errors, you do this by right-clicking on the redsn0w application and selecting XP Compatability.
Update: redsn0w 0.9.6b6 has been released and all those who wish to unlock iPhone 3GS or iPhone 3G should use that version instead since it will provide for better battery life.