Oop, I thought you had T-mobile. I guess that I just saw it in someone else's posting. Yes, take the phone to cingular (at&t). They also have an international calling discount plan. For $5 per month you will receive much better international rates on calls when outside the u.s. It is not a contract, you can add it for one month and cancel it without any hidden fees. Ask the sales associate about it when you go in.
Every country has their own country code that you will have to dial first. Lots of "fluff", but easy.
I bought a TracFone for my son to use, and we also have another one I bought for my wife to use during her hospital stays last year. I agree - they work great and frankly when my current Verizon contract expires I am thinking of going full time with the TracFones - much cheaper over the course of a year too.
A couple of cruises ago we took my daughter. She stayed on the cell phone 24/7 with her boyfriend. Everytime we got near a port, she was checking her messages, etc. Luckily it was at her expense, not mine. I never got so sick of anything in my life. I say leave the cell phones at home. I may be old-fashioned, but can't these people wait until we get home to chat?
We don't use a cell phone on the cruise, but need it to contact our limo driver once we return to port. The usual drill is they want you to call them XX minutes before you leave the ship so they can get in position. So - we need to carry a cell phone with us.