I called AT&T today because I am also going out of the country. In my case, I will need my phone on, and so I asked about their INternational plans. Luckily, they are prorated, so you can signup before you go, and then cancel when you return. Did you look at this: International calling rates and packages | Wireless from AT&T, formerly Cingular
Also, call 611, they were very helpful.