If you are traveling you may want your iPhone ot work over a network other than your home network. Fortunately, this is very easy to do with the iPhone 3G or 3GS. Your destination will likely have GSM in a different frequency than in your home country, since GSM frequencies are different all over the world. Your iPhone should switch between the frequencies automatically and allow you to select a different network.
Step 1
Turn your iPhone on and allow it to boot up.
Video of the Day
Step 2
Enter the Settings menu. It has an icon that looks like gears.
Step 3
Select carrier and choose the carrier or network you would like to use. If your iPhone does not have this option, enter the "General" menu. Again, it has a setting that looks like gears.
Step 4
Select the option labeled "Network." It is a few down from the top, but has no icon. Select the network you wish to use, and your iPhone will start to communicate over that network.
Step 5
While you are in the menu turn off Data Roaming to prevent racking up charges as your iPhone does simple things like checking for email.
Video of the Day