What settings = no data charge?

AT&T will add a data plan regardless of whether or not you use it. Their network recognizes it as a iPhone and will add a data plan.

 

If you are using the phone on AT&T, once they go to activate it with their SIM, they will be required to choose a data plan. It is a requirement for all smartphones on AT&T to have a data plan, not just the iPhone.

The only alternative that I'm aware of is JB and that allows you to make some changes to disable data. I'm not familiar with them since I'm not into JB.

 

Pay as you go is probably the best option, especially if the rumors of AT&T automatically adding the data plan are true.

 

If you can activate without a data plan, just flip the switch that says "cellular data" to off in the network settings.

 

or you can change the APN settings to anything but the ones o2 advise

Pay & Go
To change your data settings:

1. From the main screen of your iPhone, tap Settings > General > Network
2. Tap ‘Cellular Data Network’.
3. Under ‘Cellular Data’, tap APN and change ‘idata.o2.co.uk’ to ‘payandgo.o2.co.uk’ (‘o2’ needs to be written with a letter ‘o’, not a zero). You don’t need to change your username and password.
4. Ignore the APN box under ‘Visual Voicemail’ – it’s not available on Pay & Go.
5. Under MMS, tap APN and change ‘idata.o2.co.uk’ to ‘payandgo.o2.co.uk’ (‘o2’ needs to be written with a letter ‘o’, not a zero). You don’t need to change your username and password.
6. Turn your iPhone off and on again.
7. If you’re using your iPhone sim for the first time, you’ll need to top up at least £10

http://shop.o2.co.uk/update/settings.html

 

In the US we only have a on/off switch. We also don't have the option for pay as you go.

 

It will......if cellular data is turned off on the phone you will not receive mms.