We are visiting the states. We want to set up an iPhone 4S (ios7, nz telecom prepay) so that it can make and receive calls and texts, but NOT use any data, except on wifi.

I've had a quick google but standing in the airport after a long flight is not conducive to careful research!

I have "mobile" set to OFF and it has received a text from telecom saying we are roaming. Carrier has gone automatically to AT&T.

What do I need to do? If anything?

Thanks for the help.