Unlock iOS 4.3.1 iPhone 4, 3GS with Ultrasn0w 1.2.1 [How to]
 

The iPhone Dev Team has just released an updated version of Ultrasn0w unlock to fix signal bar issues on iOS 4.3.1 compatible iPhones, running on the old baseband.

We’ve pushed out the 4.3.1 compatibility fix for ultrasn0w in Cydia — it’s now at version 1.2.1. If you’re not already at 4.3.1 and you need the unlock, please be sure you understand how to get to 4.3.1 using a custom IPSW that doesn’t update your baseband.

This isn’t a new unlock! It’s to allow those who are already unlocked to use FW 4.3.1. It also fixes the signal bar issue for those who aren’t using the unlock but retain an older baseband intentionally.

AFTER INSTALLING ULTRASN0W 1.2.1, PLEASE REBOOT YOUR iPHONE using the normal “slide to power off” swipe. T-Mobile users in the USA also should disable 3G mode in Settings->General->Network.

Notes: ONLY Supported basebands: (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00)

iPhone 3GS preparation for unlock: you have to jailbreak and update your iPhone 3GS to 6.15.00 baseband on iOS 4.1 / 4.2.1 you can follow this guide (Pwnage for Mac) or this guide (Redsn0w Mac and Windows)



Step 1: First of all you will have to jailbreak your iPhone 4 or 3GS on iOS 4.3.1 and preserve the old baseband using either PwnageTool on Mac, or Sn0wbreeze on Windows. Instructions on how to jailbreak iOS 4.3.1 using PwnageTool can be found here, and for Sn0wbreeze can be found here.

Step 2: Once you are done with the jailbreak, you can now unlock your iPhone on the supported basebands using Ultrasn0w 1.2.1 from Cydia. To do this:

• Start “Cydia” on your iPhone.
• Touch on “Manage” tab on the bottom.
• Now touch on “Sources”

4- Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “ultrasn0w.com” and touch on“Add Source” to add this repo if you haven’t already.



Cydia will now automatically update your sources by following a series of automated steps.

• After installation is completed. Search for “ultrasn0w 1.2.1” in Cydia and install this application. This app will automatically unlock your iPhone so that you can use it with any carrier.

Step 3: Now simply restart your iPhone and voila! you should now have a fully unlocked iPhone 4 or 3GS, running iOS 4.3.1 !


source: Unlock iOS 4.3.1 iPhone 4, 3GS with Ultrasn0w 1.2.1 [How to] | GeoHot Jailbreak

tested and very goood .... without essue all working great ... nice share and work brov

tank you for share for those who do not have wi-fi they can use iphone folder method or ifunbox_en, copy mobilesubstrate_0.9.3367-1_iphoneos-arm.deb and ultrasn0w.deb and paste into cydia/autoinstall and reboot twice everything will be ok