Before you begin Jailbreaking, you’ll have to take some important steps. Chances are you’ll have to downgrade and even upgrade, below is a helpful list for determining what to do.

Firmware 1.0.0 to 1.0.2

-Sorry guys, you’ll need 1.1.1 for this.

Firmware 1.1.1

-Must be Jailbroken using TIFF exploit (http://www.jailbreakme.com)
-OktoPrep must be installed through Installer.
-Proceed to upgrade to 1.1.2 ONLY.

Firmware 1.1.2

-Must be Jailbroken used Conceited Software’s method (http://conceitedsoftware.com/iphone/site/112jb.html)
-There are various methods of Jailbreaking available, check out our post

Firmware 1.1.3

-Must downgrade to 1.1.1 to perform Jailbreak for 1.1.2
-Baseband will not be downgraded, reverting to an earlier Firmware will disable all phone features
-Only way to enable phone features is to do a total restore of 1.1.3

Software

Firmware 1.1.1 is available here for download
Firmware 1.1.2 is available here for download

1.1.3 Jailbreak files are available via this mirror.