3G iPhone Usable with other 3G card?

[Stumanbmx]

Here is the deal, I am being offered a 3G iPhone for an excellent price. I currently have a contract with AT&T. I am already on the 3G network but do not want to pay for unlimited data. I was wondering if I could just insert my 3G SIM and be off on my merry way? Or do I have to jailbreak it? Or is it completely impossible?

Thanks

[Cali_fresh]

You will need to add the Data plan and since your already with AT&T there is no need
to unlock the phone.

[Stumanbmx]

So there is no way around the data plan even though I'm not buying the phone from them?

[idolpunk]

no, there is no unlock for the 3g so no way of getting around activation