The Dev Team just released an update to their UltraSn0w unlock. Unfortunately, this time it’s not as easy as downloading and installing UltraSn0w to unlock the iPhone. Below is a step by step guide to prepare iOS 4.2.1 on iPhone 3G, 3GS using Reds0w for unlock using Ultrasn0w.

Note : The unlocking tutorial is above.

First we will update the baseband to iPad 06.15 and jailbreak the iPhone with Redsn0w. After the device is jailbroken, we can use Ultrasn0w from Cydia to unlock your iPhone.

Warning :

* There is no way to come back down from 06.15. You will be void your warranty if you do so.

* If a future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).

* Starting with iOS 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail).  You will need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).

Redsn0w supports :

* iPhone 3G or iPhone 3GS on baseband 04.26.08, 05.11.07, 05.12.01, or 05.13.04
* iPhone 4 on baseband 01.59.00

Requirements :

* iPhone 3G/3GS firmware 4.1
* iTunes 10.1
* Redsn0w 0.9.6b5

Note : All download links are at the end of the post.

Unlock iPhone 3G(S) On iOS 4.2.1 With Ultrasn0w And Redsn0w [How To] :

1) Download iOS 4.2.1 for your iPhone.

2) Download iTunes 10.1 and install it.

3) Save the SHSH blobs if you are still on iOS 4.1 or below.

4) Update/restore your device to iOS 4.2.1 via iTunes.

5) Download Redsnow 0.9.6 beta 4 and run it.

6) When asked for iOS firmware, point the redsn0w to iOS 4.2.1 downloaded in first step. When you receive a pop-up message, click on Yes to confirm the baseband change.

7) Click on next and select “Install Cydia” and “Install iPad Baseband” options. Optionally you can also select any other option available for your iPhone.

8) At this step make sure that your phone is switched off and plugged into the computer. Follow the onscreen instructions to put the idevice into DFU mode.

9) Let Redsn0w complete its process. Once completed your iPhone will restart and you will find your iPhone jailbroken on iOS 4.2.1.

Now if you have iPhone 3GS new bootrom you will have to connect it with Resn0w and select the “Just boot tethered right now” option to get the jailbreaked state on every boot.

Now, you have successfully jailbroken your iPhone, follow this tutorial for unlocking.

Unlock iPhone 4, 3GS, 3G Using Ultrasn0w [How To]

Downloads Links :

Redsn0w 0.9.6 beta 5 (Windows) 
Redsn0w 0.9.6 beta 5 (Mac)