Just so you are aware, you do not 'have to' buy the "international minutes" to be able to make calls internationally - the regular $J phone cards work fine to make international calls. the 'international minutes' package is really intended as a savings deal for longterm use, for someone who will be there for a while, or who really likes to talk a LOT, lol. But just for a week, there's no need - of course you certainly can if you want to, but it's not necessary. A $J500 phone card is likely all one would need if just making 'check in' calls.Put $500J on the phone and get 600 minutes of international time for $1200J.
and i concur with seveen - never use your home cell phone - it's the roaming charges that kill you on the bill - no matter WHAT kind of 'deal' your phone company 'says' they have for 'per minute' charges. It's always much cheaper to just buy a cheap local phone. And safer too..... fancy phones are targeted items. I know for me personally, i don't want my good phone to be 'seen' out and about, and never want it to be out in the hot sun, or near the sand or water.