According to the iPhone testing results, if 1.0.2, 1.1.1, 1.1.2 OTB firmwares are upgraded to 1.1.3, their system can be downgraded to the original ones (Modem is not downgraded), but the operation is different from the original. Now we will show the operations.

Testing Inviroment：Windows xp sp2＋iTunes 7.5

iBus Download

1.　　First you must have an iphone which has an upgraded firmware 1.1.3. Download the firmware you need to downgrade (All version of firmware must be downloaded), and connect your iPhone with your computer. After connection, shutdown your iphone. Then press "Home" and "Shut" at the same time for 10 seconds, release "Shut" and still press "Home" until iTunes gives you a hint that your iPhone should enter restoring mode.

2　　Choose the firmware you want to downgrade in the hop-up window, click "confirm", then iTunes will restore your iphone. If there appears a message hinting you "can't install, unreasonable mistake (1)", you need use iBus to recognize your iphone.

Click "start to downgrade 1.0.2 firmware" according the following picture.

The screen becomes white, then iBus will come to the following picture.

3.　　Press "Shift" on the keyboard and click "Restore" with mouse, find the firmware you need to downgrade in the hop-up window, click "Confirm". Now iTunes will restore you iPhone, that means it is downgraded.

4.　　After downgrading, iTunes will give you a hint "10105" or  "1011" mistake. Don't worry, that means you has successfully downgraded your iPhone. Shutdown iTunes.

5.　　Now your iPhone must be in restore mode. Back to normal mode, you should use iBus. Shut iBus and reopen it if you put iBus under "Close" state. Click "Introduce you iphone"

If the screen is red, downgrade is sucessfule; the screen is green, it must downgrade again (restore)

　　If the screen is green, then reoperate it agian from step 3 until the screen is red and comes to normal mode. Then you can do what you want, such as hacking.

　　Hint：Normally, restoring(downgrading ) twice will come to normal mode. But pay attention that this tutorial only help you downgrade system, not Modem.