Many have had the unpleasant experience of receiving a large cell phone bill upon returning from an international trip. T-Mobile has the best deal going: their phones include unlimited international roaming, and they mean it. I’ve used my T-Mobile phone so far in Australia, New Zealand, and Italy. I always had a usable connection. They give 3G speeds, which is fine for email and basic web browsing. They charge U.S. $.20 a minute for telephone calls, although one can avoid that by using Skype.
One thing to watch out for — cruise ships. As long as one is in range of shore, T-Mobile works splendidly. However, if one on the high seas, your cell phone will connect to the ship’s cellular system. On Princess the name is Maritime Communications. Data charges were $15 per megabyte of data. I forgot once to switch data roaming off. The result was 4 incoming e-mails and a $7.00 charge.
Be sure to turn data roaming off if you are not close to shore.