iOS hacker iH8sn0w has just released sn0wbreeze 2.3b4 jailbreak that brings working unlock on iPhone 3GS baseband (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00) running iOS 4.3 firmware . Follow the guide to “Tethered” jailbreak your iPhone 3GS (Old and New Bootrom) and then use ultrasn0w to unlock your device.

Earlier, Ultrasn0w was broken on iOS 4.3 but Steven managed to the patch ultrasn0w using Ultrasn0w fixer developed by msft_guy and then integrated with sn0wbreeze utility.

Full Change Log

• ultrasn0w now works for basebands (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00)
• ultrasn0w is NOT compatible with the folllowing basebands! (02.10.04 / 03.10.01 / 04.10.01 / 05.14.02 / 05.15.04)
• Upgrading your iPhone 3GS baseband to the 06.15.00 iPad baseband hack to unlock MAY cause you to lose your GPS!
• Fixed minor GUI + iBooty bugs.

Step 1: Download Sn0wbreeze 2.3b4

Step 2: Jailbreak your iPhone 3GS (New Bootrom) device using guide posted here. For ‘New Boorom’ you need to tether boot your device using iBooty. For Old Bootrom iBooty is not required as it supports untethered jailbreak.

Step 3: Follow (Step 2-7) to unlock your iPhone 3GS using guide posted here

Note: If your iPhone 3GS is running on BB 05.14.02  or 05.15.04, then make sure you first update your baseband to 06.15.00 and then unlock it.

If you face any trouble while jailbreaking your device, just drop a message in the comment section. Alternatively, you can follow Jeffry, the author of this post, on twitter and facebook fanpage.  If you’d like to contact him, Twitter is the most effective means of doing so. You may also like to check out:

• How Gevey SIM Unlocks iPhone 4 On Baseband 2.10.04 / 3.10.01
• New Exploit to Unlock iPhone 4 Permanently Discovered – FAQ
• Jailbreak iPhone 4 iOS 4.2.1 with PwnageTool 4.2 & Unlock with Ultrasn0w [Mac]