Fuzzyband Downgrader is a simple and free application that can be used to downgrade your iPhone’s baseband so that you can use it on unofficial carriers (such as T-Mobile). BUT, Fuzzyband doesn’t work for every iPhone out there. Continue reading to find out if you’re able to use Fuzzyband.

With the recent 3.1.3 update from Apple (which upgrades the baseband to 05.12.01), people have been going crazy for an unlock. Fuzzyband is able to downgrade the baseband, but only for a small number of iPhone’s:

• Will only work on an iPhone 3G with the 05.08 bootloader.
• A very small number of iPhone 3G’s actually have this bootloader.

Still confused?

• If you have a iPhone 2G, then you can just use BootNeuter, since it is a permanent unlock.
• If you have a iPhone 3G, but aren’t sure of your bootloader, you can install Fuzzyband, and it will tell you.
• If you have a iPhone 3G and do have this bootloader, you can downgrade your baseband from either 05.12.01 (latest), 05.11.07 (3.1.2), to 04.26.08.
• If you have a iPhone 3GS, then you’re out of luck.

So, if you’re not sure whether or not your iPhone 3G has the 05.08 bootloader, you can install Fuzzyband to find out (and possible downgrade your baseband!).

You can go ahead and install Fuzzyband right now for free from Cydia. Make sure you install “Fuzzyband”, not “Fuzzyband 3G”. It’s about 7.5MB in download size, and the current version number is 3.1.3-1 (see the screenshot above as a reference). Once it’s installed, you can immediately run Fuzzyband; A reboot or a respring is not required.

You can then tap on the Fuzzyband icon on your SpringBoard to run it.

Upon load, it will query the modem to gain various version information and whatnot. This process can take a couple of minutes, so don’t interrupt the process, and be patient.

When it’s done, it will then tell you whether or not your device will work with Fuzzyband. With the case with my iPhone 3G, it is not compatible, so an unlock is currently not possible by any unlocking method. If your device IS supported, you should see a downgrade button. This will downgrade your baseband from either 05.11.07 (3.1.2) or 05.12.08 (latest) down to 04.26.08. You can then install ultrasn0w to unlock your device.

Good luck, and post back with your results (whether or not you can actually use Fuzzyband).