*This is only for 1st Generation iPhones that have been upgraded… not for 3G iPhones*

1. Download iTunes 7.5 from here: Direct Download iTunes 7.5 to Activate iPhone Anywhere Internationally » My Digital Life
2. Uninstall your current version of iTunes and reboot your PC.
3. Go to My Documents > My Music > iTunes and delete the file called “iTunes Library.itl”
4. Install iTunes 7.5

Note for OSX users:
If you are on OSX and want to attempt to downgrade your iTunes, you can try these steps:

Load up Terminal and type the following:
killall iTunesHelper
sudo -s
rm -r /Applications/iTunes.app
rm -r /Library/Receipts/iTunesX.pkg
rm ~/Library/Preferences/com.apple.iTunes*
rm -r /Applications/iTunes.app
rm -r /Library/Receipts/iTunesX.pkg
rm ~/Library/Preferences/com.apple.iTunes*
rm -r /System/Library/PrivateFrameworks/MobileDevice.framework

5. Download the 1.1.4 restore file from the here http://www.modmyifone.com/forums/dow…o=file&id=2231 if you don’t already have it.
6. Put your phone into DFU mode using the following steps
a. Plug your phone into iTunes (ignore the message that pops up)
b. Power the phone OFF
c. Hold power and home for EXACTLY 10 seconds
d. Release power (continue to hold home)
e. iTunes will recognize iphone in restore mode (you can let go of home now)
7. Hold shift and click Restore – select the 1.1.4 firmware file you downloaded
8. After it’s done restoring you will get error 1015 and the phone should be in recovery mode (iTunes logo with cable)
9. Important! Hold shift and click Restore and select the 1.1.4 firmware file and RESTORE AGAIN.
10. After it’s done open iLiberty “other tools” tab and click “jump out of recovery mode”. (note – if you didn’t restore TWICE as instructed above the phone won’t jump out of recovery mode)
Note: On a Mac you can use Independence to kick out of recovery mode. http://code.google.com/p/independence/downloads/list

OK, you now have a phone with 1.1.4 Firmware and the 4.05.04 baseband. Now we have to downgrade the baseband

11. Download KiPhone
*Unzip all files into a folder before you run the program or it will fail*
12. Run KiPhone with Debug Boot and iErase options checked. (Leave the box for downgrade UNCHECKED)
13. Plug your phone into iTunes and shift+click restore to 1.1.4 AGAIN. This will write the correct 4.04.05 baseband to you phone. (You may have to put your phone into recovery mode manually for iTunes to let you restore – hold power and home until the phone reboots – continue to hold until you see the iTunes logo)
14. Your phone should now be factory 1.1.4 with the matching baseband – all you have left is to jailbreak/unlock with you method of choice.

Guide by modmyifone.com