The carrier unlock required a complete rewrite of the software because of Apple's new baseband OS for the updated phone.
It is important to note that users who unlock their iPhone 4 can use T-Mobile's cell network but not its high-speed 3G data.
Ultrasn0w 1.0 comes with instructions, courtesy of RedmondPie:
How to: Jailbreak iPhone 4 on iOS 4.0.1:
-Step 1: Unlocking requires that your phone is jailbroken on the latest firmware. Follow the complete guide posted here to jailbreak your iPhone 4 on iOS 4.0.1 / 4.0 using JailbreakMe 2.0.
How to: Unlock iPhone 4 (Any Baseband) on iOS 4.0.1:
-Step 2: Once you are done with the jailbreak, you can now unlock your iPhone on any baseband using Ultrasn0w 1.0-1 from Cydia. To do this:
-Start “Cydia” on your iPhone.
-Touch on “Manage” tab on the bottom.
-Now touch on “Sources”
-Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “http://repo666.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 1.0-1” 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.
As with all unlocking and jailbreaking guides, please use caution as there is always a chance of messing up your device.
Written by: Andre Yoskowitz @ 4 Aug 2010 19:49
