Q: Does anyone know if this will mean that I will have to start paying for data on my iPhone 3gs on tmobile?

The only iPhone that will be fully supported on T-Mobile is the iPhone 5. How are you getting data now, if you are not paying for it?

Updating your iPhone has nothing to do with having it unlocked, which is what would be needed to use the phone on carriers other than the one it is locked to.

If you want service on T-Mobile for calls and such, their plans also involve data. You cannot sign up for their network without a data plan.

Fully functional means data access, which means you have to pay for it.

Nobody here is going to help you steal service.

If you mean you want only phone and texting, without data access-you need to call T-mobile and ask.

No one here among your fellow users know the answer to your question. Why don't you just ask T-Mobile?

No one here can answer that. Ask T-Mobile.

You don't trust them? Sounds like you have the wrong carrier, then.

Buy a dumb phone.