How to Extract iPhone Firmware Files
- 1). Download the iTunes program from the Apple website. (See Resources.) Double-click the file once downloaded. Follow the menu commands to install the program onto the PC's hard drive. Restart the PC once the installation is done.
- 2). Launch the iTunes program by selecting it from the "Start" > "All Applications" pop-up menu
- 3). Plug one end of the iPod cable into the iPhone. Plug the other end of the iPhone cable into a USB port on the PC.
- 4). Click once on the icon of the iPhone that is below "Devices" in the left column of iTunes. Click the "Summary" tab at the top of iTunes. Click the "Update" button in the middle of iTunes, beneath "Version."
- 5). Click the "Download and install" button on the pop-up window that appears to download the firmware file package to the iTunes folder on the PC's hard drive. This procedure could take anywhere from 10 to 15 minutes or more, depending on the speed of your Internet connection.
- 6). Continue waiting as a progress bar in an information panel at the top of iTunes details the extraction process of the files from the firmware file package. Continue waiting as the firmware files that have been extracted are installed into the iPhone.
- 7). Right-click the iPhone's icon when the information panel states that the firmware process is completed. This will have been accompanied by a rebooting of the iPhone.
- 8). Select "Eject" from the pop-up menu. Quit iTunes. Remove the iPod cable from the iPhone and from the USB port of the computer.
Source...