Good news folks.  pH, BigBoss, and EvilPenguin have created a tool to downgrade your baseband from 02.30.03 to 02.28.00.  What does this mean for you?  Well, if you upgraded (on purpose or accidentally) to 2.2.1 - then you have 2.30.03, which is not supported by yellowsn0w.

The only downside to this:  the iPhone 3G has two bootloaders:  5.8 and 5.9.  According to http://thebigboss.org, “if your iPhone was manufactured before September (2008), you are 5.8. Otherwise, you are 5.9 (that can’t be downgraded)”.

A quick and easy way to tell when your phone was manufactured is by looking at the 11 digit serial number located on the lower back of the phone.  The first two digits are the factory ID (where it came from), and the next three are date information.  The rest of the numbers are irrelevant for our purposes of downgrading

It’s digits 3-4-5 of your 11-digit serial number. The first two are the factory ID of which it was made in, and the next three are date info. I don’t know what the rest of the numbers are for.

Example:  xx832xxxxxx.  The 8 represents the year 2008.  This is the first good sign for your iPhone 3G.  The next two numbers is the week it was created.

From what I’ve come up with - if you have lower than week 36, you should be okay.  Week 36 is the end of September.  Can we get some comments to confirm this?

So to install this beautiful piece of work, you can find it on TheBigBoss repository on Cydia.  It’s called “3GBBD” (3G Baseband Downgrader).  Just download and click go - and you should be on your way!

These notes are DIRECTLY from the http://thebigboss.org post:

WARNING: This tool is NOT a toy. Just use it if you can’t use Yellowsn0w on your 2.2.1 iPhone 3G. Otherwise, DO NOT INSTALL IT JUST TO TEST! YOU HAVE BEEN WARNED!

Edit: if you have bootloader 5.9, this should not cause any harm. It should simply fail. You will then have to reboot your iPhone and should be back up to where you were before running the tool.

Big thanks to pH, EvilPenguin, and BigBoss http://thebigboss.org for this wonderful tool!

“redsn0w is currently in beta as it relies on the user running it from the command line, but this new redsn0w functionality is being added into our GUI applications.” - iphone-dev

I took a gander, and what do ya know, redsn0w beta is live for Linux, Windows, and Mac!  I am currently torrenting the files - when they’re done, I’ll upload them and post the links here.  Let us know your results:  success, fail, or what have you.

theiphoneproject mirrors

redsn0w for Windows is here or here SHA1 sum - ee20e5879bcc00b9e7ce29da85fd168eec479d1b 4002959182759d3d18482671e62d7a3799670c5a

* the iphone-dev team accidentally released the windows version with a few linux binaries, so they had to repack and rerelease.  You’ll need to redownload.

redsn0w for Mac OS X is here or here SHA1 sum - 04edb5465526afc00508d18125094725a76dd91c

redsn0w for Linux is here or here SHA1 sum - d775291a7624c44d3b46fc5ff8595d18b05c3de9