Ah, the things AT&T will not tell you when you are traveling abroad - you might buy a "plan" but you are still not only paying for talk minutes but for phone and data roaming. I too have an IPhone 4 - when I turn it on airplane mode on my last leg of my trip it stays in that mode until I'm on US soil again.

I've always used my Jamaican cell phones for local and international calls. Digicel has a decent plan, actually more than decent - last year it was 1100JMD for 1000 minutes of talk time to the US. Its a monthly plan but for that money even if you are just staying a week or two its a very cheap way to phone home.