Every summer brings the same horror stories. An unwary traveler goes to France, or maybe Egypt, perhaps Thailand, and when he returns home, there is a stunning cell phone bill that may cross well above $1,000.
Worst still, a lot of these travelers incurred charges without being aware they were doing so. Check your phone. A lot of apps automatically update their data feeds. That's email, Twitter, Facebook and plenty more. At home, probably, those costs are nil, just part of monthly service fees. Out of the country, however, you may pay big time for data "roaming" charges.
The key to dodging those fees: pick the cellular plan you need before you go. Plans you already have, or at least have heard of, probably will do fine.
No, you don't have to do anything fancy such as buy foreign SIMs and pop them into your unlocked phone. Most phones are not unlocked - they are paired to a particular carrier - and they won't accept a foreign SIM. If you are overseas for an extended period - months not days - it is worth the hassle to navigate this maze. But for a quick business trip or vacation, it's a lot simpler to stick with a U.S. based carrier.
Understand this: voice calls overseas are expensive, sometimes upward of $1 per minute. But we don't incur those charges unbeknownst to us. And the way to avoid these charges is just don't answer the phone for incoming calls, and make all outgoing calls using WiFi and Skype or Google Voice, at rates ranging from free to a couple pennies a minute for most calls. Problem solved.