How can I downgrade my iPhone 3G baseband to 02.28.00?
If you've used Apple's iTunes update process to update your iPhone 3G to OS 2.2.1, you may have noticed the baseband was also updated from 02.28.00 to 02.30.03. Unlocking a jailbroken iPhone with yellowsn0w to use it on additional wireless carriers requires baseband version 02.28.00.
The solution is now available on Cydia: 3G Fuzzyband Downgrader. This software will safely downgrade any newer baseband to 02.28.00.