When traveling abroad, it is important to disable the roaming data and/or voice capabilities of your iPhone in order to avoid unnecessary overage charges on your next bill. Your iPhone performs many tasks in the background (i.e. checking for new mail, updating your contacts and calendars, etc.), completely transparent to you, that make use of your phone's internet capabilities. Turning off this connection when in foreign countries where your cell plan does not provide coverage can save you a lot of money.
To do so, open the Settings application from your Home screen, and proceed to General, Cellular, then Roaming.
Change the Data Roaming option to OFF. If you wish to disable Voice Roaming, disable that as well, then tap the Cellular "back" button in the upper left corner of the screen.
Done! Remember to do the opposite when you return home to re-enable these features.
If you have device other than an iOS-based one, stop on by and we'll show you in person how to accomplish this on your beloved device.