Overseas Calling Charges: AT&T and T-Mobile handsets can accompany you to Europe and to other countries that support GSM/GPRS smartphones. But if you don't plan ahead, you're likely to be blindsided by a seriously huge bill for roaming charges.
AT&T customers can bring down rates for voice calls by paying $6 a month for AT&T World Traveler Service. Voice calls overseas vary in price, but AT&T, for example, normally charges $1.29 per minute for calls to and from France; its World Traveler subscribers pay 99 cents a minute.
One tip to keep voice roaming charges down: If you're not able to pick up calls when traveling (such as when you're asleep), power down your handset, or at least put it into airplane mode so that it doesn't show up on a carrier network. Once an incoming call hits the overseas network in pursuit of your handset, you'll be charged at overseas rates even if the caller just winds up leaving voicemail. In fact, you might even incur a double charge--when the unanswered call bounces back to voicemail in the United States, the overseas carrier may charge for sending the call back. But if the network can't find your phone, the call will go straight to voicemail, incurring no foreign roaming charges.
Making calls using Skype or another voice-over-IP service can save you money if you can find a Wi-Fi network (which is generally a good strategy to save money on data services while traveling).
Overseas Data Charges: Unlimited data plans from U.S. carriers don't apply to data services on overseas networks: AT&T's basic charge for international data roaming is 1.95 cents per kilobyte of data sent or received. That's (almost) a whopping $20 per megabyte--and a single digital image can easily cost that much to e-mail.
Fortunately, AT&T offers international data roaming packages that, while still expensive, significantly undercut the pay-as-you-go rate. Consider buying one before you leave if you plan to use your iPhone, BlackBerry, or other smartphone for e-mail and Web browsing. The packages range in price from $25 for 20MB to $200 for 200MB--and even if you exceed your allotment, the overage rate of half a cent per kilobyte is still cheaper than the usual rate of 1.95 cents.
iPhone users who want to keep an eye on data usage while roaming should go to Settings/General/Usage and look under Cellular Network Data. Do this when you first arrive at your overseas destination, and you can reset all the statistics to start tracking your use from then on. (Better yet, try it out before you go to get an idea of what your typical monthly data consumption looks like.)
Also bear in mind that you don't have to incur roaming charges if you simply leave your handset at home. (Sprint and Verizon Wireless customers who don't have dual-radio phones must do this anyway, as those carriers' CDMA/EvDO networks are incompatible with the GSM/GPRS networks most other countries use.) If you need a phone, buy a cheap prepaid phone in the country you're visiting. It will certainly save you money on both voice and data--but remember, you won't be reachable on your usual cell phone.
The Fine Print: When was the last time you really looked closely at your phone bill? This is a good way to see whether your phone usage is in line with your plan. You might find, for example, that you're not even close to using the number of minutes you've paid for. And while you're at it, look carefully for all the little charges at the end to make sure you're not paying for something you never wanted. Case in point: A few years ago a lot of people complained about unsolicited roadside assistance service charges. Who knows what other charges may be lurking now?
For more carrier-related gripes, check out 10 Things We Hate About Wireless Carriers.