iPhone Dev Team announced just a few minutes back that they were working hard to release tools to jailbreak and unlock iOS 4 and had warned users who relied on software method to unlock iPhone to avoid upgrading to iOS 4 until they have tested their tools with all relevant devices.
iPhone Dev Team announced the following via Twitter:
Ultrasn0w 0.93 released! Cydia repo is repo666.ultrasn0w.com. Works with basebands 04.26.08 thru 05.13.04
So if you have jailbroken your iPhone running iPhone OS 3.1.3 or earlier (upto iPhone OS 3.0) then you should be able to install Ultrasn0w from Cydia to unlock your iPhone.
Here are the steps that you can follow:
Please add the repo repo666.ultrasn0w.com to Cydia. That last “o” is actually the number zero “0”. If you use the letter “o” you’ll get an error.
Then search for ‘ultrasn0w’ in Cydia and install ultrasn0w.
T-Mobile USA users should disable 3G before using ultrasn0w.
This should successfully unlock your iPhone.
As always, let us know how it goes.
Thanks everyone for the tip![via Dev Team]