On my iPhone 4S on the settings tab where you turn on your 3G there's a button to turn Cellular Data on/off and another button for my 3G. If I only have cellular data on and not 3G will it add to my contract bill because all I have is 100MB so I really don't want to go over and pay more than I already have to so basically if I have cellular data on will it eat away at the 100MB I have?
Read more: Will this add to my 3G data allowance?