If you’ve installed iPhone 3.0 app from Torrent, then you may have ended up with a locked phone. Follow the steps below to roll it back to the old firmware. Note: Your iPhone 3.0 OS backups (your phone settings, unsynched photos, text messages, etc) will not be compatible with 2.2.1 once you go back down. So make sure you have a backup from the 2.2.1 days to restore from, or else you'll be starting from scratch.
iPhone EDGE: If you're running OS X 10.5.6, you'll need to do the USB DFU fix outlined in our jailbreaking guide before proceeding.
- With your phone plugged in, put it into DFU mode by holding both the power and home buttons for 10 seconds, then releasing power and continuing to hold down home until iTunes recognizes a phone in "recovery mode."
- Download the 2.2.1 firmware .ipsw file from Apple. Hold down option (Mac) or shift (Windows) and click on restore. Choose the stock iPhone 2.2.1 file you just downloaded.
- Let it do its thing, and you should be in business. Restore your backup should you have one, and proceed to jailbreaking if you want to.
More info: iPhone 3G