We had previously seen how to jailbreak iPhone 3G on iOS 4 using redsn0w 0.9.5b5-3 on Windows, but it didn’t support iPhone 3GS. PwnageTool 4.0/4.01 supports iPhone 3GS but you must be on already pwned 4.0 Beta or 3.1.3 or lower firmwares. This means if you had used Spirit to jailbreak iPhone 3GS 3.1.3, then wait for a different release.
Guide to Jailbreak iPhone 3GS with iOS 4 using PwnageTool 4.01
Backup your data using iTunes.
Download PwnageTool 4.01 [mirror]
Download iPhone 3GS iOS 4 Final Firmware
Launch PwnageTool 4.01 and select your device
PwnageTool 4.0 will automatically detect the correct iOS 4 [ipsw] for your iPhone 3GS or 3G or you can use the browser to locate it.
When PwnageTool asks “Do you have an iPhone contract that would activate normally through iTunes?”, click on “No” if you are not on official carrier or “Yes” if you are on official carrier.
PwnageTool 4.0 will now prepare a custom iOS 4 firmware for iPhone 3GS.
Wait for “ihaz Success” screen which will confirm the completion of ipsw file creation.
Once the .ipsw file has been created, you will now have to restore your iPhone to this custom firmware 4.0. Click on your phone icon from the sidebar in iTunes. Now press and hold left “alt” button on the keyboard and then click on “Restore” button in the iTunes and then release the “Shift” button. Select that custom .ipsw file and click on “Open”.
That’s it! Just wait for iTunes to complete the jailbreaking for you! Alternatively, if you have iPhone 3G or iPod touch 2G, you can follow our guide to jailbreak iOS 4 using RedSn0w 0.9.5b5-3
Unlock iPhone on iOS 4.0
Follow our previous guide to unlock iPhone 3GS on iOS 4.0 on any baseband using ultrasn0w 0.93 Disclaimer: The above guide is for educational/testing purpose only. We are not in anyway responsible for any probable damage caused to your device. Use at your own risk.