How to turn off Cellular Data on iPhone

So what should you do to make sure that your iPhone doesn't connect to any cellular data network? Well first, you should turn off any push notifications. You can do that by going to settings, "mail, contacts, and calendar", fetch new data, and then turning it off.

But in order to be REALLY, REALLY, sure, just put a different apn on your cellular data network. You can do this by going to settings, general settings, network, and cellular data network. Just add another letter to the default apn and your iPhone shouldn't connect to your carrier's servers and use up data.