[Photo/The New York Times]

Last week's column suggested ways to save when calling home from abroad. This week I'll tackle data roaming fees, which wireless providers charge when customers use their phones outside their service area. With travelers using smartphones and other wireless devices abroad in the same way as they do back home (to check e-mail, to update Facebook and Twitter and to pull up online maps), the skyrocketing fees are taking many by surprise.

Jeff Gardner, the small-business owner I wrote about last week, was one such customer. Over four days in Jamaica he racked up an $11,000 Verizon bill after trying — unsuccessfully — to text with his cellphone and to check e-mail on his laptop using a wireless card. The biggest culprit: roaming fees.

The fact that Verizon has lowered Mr. Gardner's bill to about $2,500 (negotiations are ongoing) since that article appeared suggests that carriers are well aware of the get-me-to-a-hospital sticker shock roaming fees can cause. In fact, Verizon says that it is trying to educate customers about how to minimize roaming costs.

Last month, for example, the company introduced an online Trip Planner that allows travelers to estimate how much text and data might cost for planned trips. (Users must list their destination, length of trip and type of phone.)

In April, Verizon created a YouTube video, "Tips for Traveling Overseas," which draws attention to its global data plans and the automated alerts it sends when roaming charges exceed certain thresholds. AT&T has upgraded its international data plans for travelers. (More on those below.)

Despite such efforts, avoiding high roaming charges requires attention and vigilance. Here are a few ways to control costs.

USE WI-FI To avoid roaming fees completely, select airplane mode or turn off data roaming on your smartphone until you are in a Wi-Fi hot spot, where you can check e-mail or use the Web at much lower costs (often free). If you were to do either while roaming, your bill would show it: an e-mail with a 5-megapixel photo, for example, would require your phone to download about 2 megabytes of data at a cost of about $20 a MB from either Verizon or AT&T.

RENT A WI-FI BUBBLE If you can't plan your trip around Internet cafes, hotel lounges or other free Wi-Fi spots, consider renting a portable Wi-Fi bubble. Tep Wireless, a smartphone rental company based in London, offers a pocket-sized Wi-Fi device that connects to local 3G signals in 16 European countries and allows you to use Wi-Fi with up to five devices simultaneously. Rates begin at $15 a day for three days (the longer you rent, the cheaper it gets) and include shipping to your home and pre-paid shipping labels for returning the device. If you are traveling in a single country like Spain, Italy or Britain, there is no limit on data use. For those touring Europe, Tep has a pocket Wi-Fi device that works in multiple countries but limits data to 50 MB a day.

For those traveling across a broader range of countries, the National Geographic International MiFi, which is available at CellularAbroad.com, offers portable Wi-Fi in more than 100 countries. Travelers pay $82 to rent the device, including two-week shipping as well as data rates, which vary by country but are less compared with roaming fees charged by United States-based carriers. Cellular Abroad also has single-country MiFi rentals with unlimited data rates as low as $12 a day, plus shipping, for travelers spending two weeks in countries like Australia, China and Italy.

For Europe-bound travelers, Tep also has rental packages for smartphones (loaded with apps like Skype, Facebook and Twitter) with rates from $11 a day for five days, including unlimited Internet and local texts, but not calls.

CONSIDER A DATA PACKAGE If you don't want to be limited to Wi-Fi in order to read e-mail or access the Internet, consider an international data package, which will allow you to roam at low pre-paid rates.

Last month AT&T introduced international add-on options that provide travelers with more than double the data provided in previous deals.

Travelers who choose an add-on, which is tacked on to existing domestic calling and data plans, now get 50 MB for $25 a month compared with 20 MB previously, and up to 800 MB for $200 a month versus 200 MB. The data packages are available in more than 100 countries.

Verizon Wireless sells similar global data packages ranging from $30 a month for 25 MB to $100 a month for 70 MB for travelers bound for Canada, Mexico, the Caribbean and Europe. Still, many of its phones are not compatible with foreign carriers. (AT&T and T-Mobile use signals that work in many other countries.) For customers headed to countries where Verizon phones aren't compatible, the company has a loaner phone for anyone taking a trip of 21 days or more. (Customers will need to order it in advance and pay the $9.99 shipping charge.) And T-Mobile sells an unlimited international e-mail plan for BlackBerry users that is $19.99 a month.

Regardless of the data plan you choose, be sure to set your phone's usage tracker to zero so that you can keep track of how much data you are using while you're gone. AT&T charges $10 for each 10 MB of data used above and beyond its international data plans. Verizon charges between $2.05 and $5.12 per megabyte of extra data.

If you don't want to worry about monitoring your data use at all, a pre-paid data package is an easy way to stick to your budget. Telestial, a communications retailer that provides wireless services for travelers, offers deals for smartphone and tablets with rates as low as $1 per megabyte in many countries, including France, Germany, Italy, Sweden, Switzerland and Britain.

To get those rates travelers must also buy a Passport SIM card ($29), which allows your unlocked cellphone to work overseas and includes $10 of credit for local calls, texts and data. Once you hit your data limit, you must add money to the card if you want to use more. You can also set up auto-loading so that whenever you use up, say, a $10 balance, Telestial will automatically load another $25 (or other pre-determined amount) to your account.

BOOST YOUR DATA PACKAGE It has recently become possible to get more out of those international data packages, thanks to new mobile tools that condense downloaded data. Onavo (onavo.com) a new Tel Aviv-based start-up, has an iPhone app that compresses users' Web, e-mail and application data. The company states that customers who buy, say, a 50 MB, $25-a-month global data package can triple the data by using Onavo.

Opera, a Norwegian browser maker, offers free data compression for Internet surfing (but not downloads or videos) via a downloadable mobile Web browser called Opera Mini, which works on more than 3,000 phones, including Android, BlackBerry and iPhone models.

Opera estimates that users with a 50 MB data plan could get up to 500 MB by surfing the Web using the Mini browser on their phone. Type m.opera.com into your phone's browser, or download it from Apple's App Store, the Android Market or Nokia's Ovi store.