How do I ensure iphone wont use cellular data? Possible Duplicate:
  How to stop an iPhone 3G from using cell data, ever?  




Travelling overseas and would like to take the iphone only for wifi purposes. I have heard horror stories of people rackin gup huge bills for roaming charges, so how do I ensure the iphone won't use cellular data/3g?
In the Settings App, go to General -> Network.

Flip the switch beside Cellular Data to OFF.

That is all. I don't have a data plan and I leave it off and have never been surprised by additional charges on my bill.