If you are looking for jailbreaking iOS 4.2.1 or iOS 4.1, this is the right place. I will guide to both jailbreaking and unlocking your iPhone. If you want to unlock your iPhone after jailbreaking, you can follow all of the instruction below. If you have a factory unlock device, then you should just follow the jailbreaking step.
Note: If you want unlock your iPhone, then before jailbreaking you must preserve your old baseband first since this iOS 4.2.1 baseband can’t be unlocked with Ultrasn0w. Click here for instruction to preserve your old baseband while upgrading to iOS 4.2.1 and jailbreaking. It works with iPhone 4 only.
Here is the guide to jailbreak iOS 4.2.1 or iOS 4.1 with Greenpois0n for Windows:
Step 1: Download Greenpois0n from here.
Step 2: Now extract the .zip file (downloaded above) and run greenpois0n.exe.
Step 3: Turn off your iPhone now and click on the “Prepare to Jailbreak (DFU)”
Step 4: Now you will have to set you phone into DFU mode. Follow the below steps:
- Press and Hold Power and Home Button for 10 seconds. Now you can release the Power button while keep holding Home button for another 10 second.
- Now you are in DFU mode.
Step 5: Click on “Jailbreak” button once your iPhone is in DFU mode.
Step 6: Click on “Done” to finish your work with your PC. It is time to check your iPhone. You will notice there is a new icon “Loader” on the springboard.
Step 7: Click on the “Loader” icon then “Cydia” then “Install Cydia”. Now wait for the system installing Cydia on your iPhone. Once the installation finished, you can click on “Remove Loader.app”.
Step 8: Reboot your iPhone and you will see Cydia icon on the springboard.
Congratulation now it is done.
If you want to unlock, you can follow our instruction here.