ATT Switcher Question

[JTM]

Next week my current contract is up w/ Verizion and I am switching to the iPhone/ATT. I already bought an iPhone and know how to activate via iTunes. Since I work in/on water (lakes, rivers, streams, etc.) I want go into an ATT store and open a new account to get a free phone for use in these situations and then activate the iPhone as soon as my new ATT account becomes active (I'm correct in that I can do this, right?). How soon after activation of the new account can I activate my iPhone?

Thanks,

~joe