Dev-Team has released UltraSn0w 1.2.4 to unlock iPhone 4, 3GS running iOS 5 firmware. This UltraSn0w update can unlock iPhone 4, iPhone 3GS on unlockable basebands running iOS 5. These are the steps to unlock iPhone 4, 3GS iOS 5 with UltraSn0w unlock.

For those who don’t know, UltraSn0w is a software unlock solution for iPhone, created by the iPhone Dev-Team, so that users can use their iPhone on any carrier other than the official ones.

ATTENTION:

UltraSn0w 1.2.4 can unlock iPhone 4 and iPhone 3GS on iOS 5 with compatible basebands only. Sadly, newer basebands aren’t supported.

Supported basebands include:

iPhone 4 baseband: 01.59.00

iPhone 3GS Baseband: 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00 (Read the note at the bottom)

UltraSn0w unlock requires your iPhone to be jailbroken on iOS 5. RedSn0w can jailbreak iOS 5 and the good thing about new RedSn0w 0.9.9b4 or later is its ability to preserve baseband just like the PwnageTool and Sn0wbreeze does.

If you’re on any of the above mentioned basebands, follow  > this guide < to Update to iOS 5 + jailbreak and preserve iPhone baseband. ***Make sure to preserve baseband***

Unfortunately, it’s still a tethered jailbreak which means you have to connect your iOS device with your PC on every reboot to boot back into the jailbreak state. Untethered iOS 5 jailbreak is expected to be released soon.

Let’s Unlock iPhone 4, iPhone 3GS iOS 5 with UltraSn0w on the compatible basebands…

How to Unlock iPhone iOS 5 with UltraSn0w

Step 1

Jailbreak your iPhone 4 or iPhone 3GS using the latest version of Redsn0w or Sn0wbreeze on iOS 5.

***Make sure to preserve baseband***

Step 2

From your jailbroken iPhone on iOS 5;

1. Open Cydia and let it load and update if it prompts you;
2. Go to Search tab and search for ultrasn0w and install it. (make sure the version reads 1.2.4)
3. Installing UltraSn0w 1.2.4 will unlock iPhone 4 or iPhone 3GS iOS 5 with baseband 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00. Once the installation is completed, reboot your iPhone.

Note for iPhone 3GS with Baseband 06.15.00:

there’s a special “trick” that iPhone3GS owners with baseband 06.15 need for iOS5.  During the new setup screens you see when you start iOS5 for the first time, you’ll be asked about Location Services.  Be sure to select “Disable Location Services” when asked!  Later on in the setup, you’ll have the chance to turn on Location Services again when asked if you want to use “Find my iPhone”.  It’s fine to turn it back on at that point, if that’s your desire (or you can always go in and enable it in Settings.app).

Also, some iPhone3GS users with the 06.15 baseband may have tried to install iOS5 using a stock IPSW (even though you should never ever try to use a stock IPSW if you’re an ultrasn0w unlocker).  If you did try this, your baseband is probably in an inconsistent state, and you’ll need to reflash the 06.15 baseband again (using redsn0w).  Be very careful if you use redsn0w to reflash the iPad baseband — don’t interrupt the process! And please avoid using stock IPSWs in the future  Unlockers should never go near stock IPSWs.