iPhone Unlock Guide: Unlock iPhone 4, iPhone 3GS, and iPohne 3G on iOS 4.2.1 With Ultrasn0w 1.2

For those of you who don’t know, Ultrasn0w 1.2 is capable of unlocking iPhone 4 baseband 01.59.00 as well as iPhone 3GS and iPhone 3G that runs on iOS 4.2.1 firmware. However, for iPhone #GS and iPhone 3G, in order to unlock you need to update your device to 06.15.00 baseband so that you can use Ultrasn0w 1.2.

For iPhone 4 users with baseband 03.10.01 and baseband 02.10.04, the iPhone Dev Team is set to launch the unlock solution for your baseband after the final public of iOS 4.3.

Ultrasn0w 1.2 can unlock a jailbroken iPhone on the following baseband:
04.26.08
05.11.07
05.12.01
05.13.04
01.59.00
06.15.00

Update iPhone 3GS and iPhone 3G to 06.15.00 Baseband for Unlock Using PwnageTool:
Step 1: You must have a jailbroken iPhone on iOs 4.1 or iOS 4.2.1 firmware with baseband number 06.15.00 using the PwnageTool 4.1.3 using this
Link:http://news.ziphone.org/stepbystep-guide-update-iphone-3gs-iphone-baseband-061500-pwnagetool-413-ios-421.html.

Unlocking iPhone iOS 4.2.1 using Ultrasn0w 1.2:
Step 1:Jailbreak your iPhone 4, iPhone 3GS, and iPhone 3G using the recently released PwnageTool 4.2 for Mac OS X or with Sn0wbreeze 2.2 for Windows
Step 2: Launch Cydia application on your jailbroken iPhone, then select “manage” and tap on “Sources”.
Step 3: Select “Edit” and tap on “Add” and type the following repository address in the sources field:
Step 4: Tap Add Source and wait for it to upgrade.
Step 5: Now make a search for ultrasn0w 1.2 (its zero (0) not an O) in the Search tab at the bottom. Tap it and press Install at the top.
Step 6: Wait for it to install and then re-spring or reboot your iPhone.

JAILBREAK & UNLOCK iPhone 3gS & iPhone 4 on 4.0 / 4.0.1 Firmware: