Updated 06/29/2010 - VERSION 4.0

 

To manually update the OS of your iPhone 3G(S):

1. Download the appropriate OS update:
• iPhone 3GS
• iPhone 3G
2. Go to the folder where the file was downloaded and double-click it uncompress it.
3. Connect your iPhone to the computer and then launch iTunes.
4. Select your iPhone under the Devices group.
5. If you're using a Mac running OS X, hold down the OPTION key and click Check for Updates. If you're using a PC running Windows, hold down the SHIFT key and then click Check for Updates.
6. Select the file that was downloaded in Step 1 and then click Choose to begin the update process.