iPhone Dev Team has released Ultrasn0w 1.0-1 to unlock iPhone 4.

This makes it the world’s first free software solution to unlock iPhone 4. iPhone Dev team had already released Ultrasn0w 0.93 to unlock all basebands since iPhone OS 3.0 including baseband 05.13.04 that comes bundled with iOS 4 for iPhone 3GS and iPhone 3G users.

iPhone Dev Team announced the release of Ultrasn0w for iPhone 4 on their blog:

Version 1.0-1 of ultrasn0w works for:

• iPhone4 baseband 01.59
• 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01 and 05.13.04

So if you have jailbroken your iPhone 4 on iOS 4 or iOS 4.0.1 using JailbreakMe then you should be able to install Ultrasn0w from Cydia to unlock your iPhone 4 for free.

Ultrasn0w 1.0-1 can also be installed by iPhone 3G and iPhone 3GS users to unlock their iPhone on iOS 4 or iOS 4.0.1 or earlier (upto iPhone OS 3.0).

Here are the steps that you can follow:

1. Users should disable 3G before using ultrasn0w.
2. Launch Cydia
3. go to Manage>sources>edit>
4. Please add the “http://repo666.ultrasn0w.com” to Cydia sources and add source.  That last “o” is actually the number zero “0”. If you use the letter “o” you’ll get an error.
5. Then search for ‘ultrasn0w’ in Cydia and install ultrasn0w.
6. after installation, reboot once and enjoy an unlocked iPhone 4( the first reboot might take longer than usual to pick the new SIM)

This should successfully unlock your iPhone.

We have already got confirmations from our readers that they’ve successfully unlocked their iPhone 4.