How to Disable Data on an iPhoneby KR Knowlin
Your iPhone's cellular data network connection is denoted by the "3G," "E" or a small circle icon in the top, left corner of the device's display. The cellular data network connection allows you to make and receive phone calls, send and accept multimedia text messages and retrieve or listen to voice mail messages. The data connection also makes it possible for you to tether the iPhone to a computer. If you disable the connection, your iPhone will not access any of these features.
Tap the "Settings" icon.
Tap the "General" tab.
Select "Network." Your Network settings page will load.
Slide the switch next to the Cellular Data field from the "On" position to "Off."