I will be leaving on a 6-week scientific field campaign to Arica (Chile) in mid-October and would like to take my iphone (2G): email, Apps and (ideally) phone usage. However, if I did this I'd want to be sure that upon my arrival back to the States that I didn't have a whopping bill from AT&T sitting in my mailbox.

One potential option that I've seen in our forum is that one can use Skype with their iPhone (
http://www.everythingicafe.com/forum...ype-35911.html) and that may probably be good enough. (btw, has anybody tried this yet?) Anyway, before I make any decisions, I'd thought I'd poll the collective wisdom here to see if there are other options.
TIA