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Make a temporary change to your monthly service plan
Most major cellular providers offer international roaming plans that can be added and removed without affecting your long-term contract. The monthly fees and prices per minute vary widely among service providers. And it may not help much: AT&T's, for example, charges $24.99 for 20 megabytes of data transfer (about 20 JPEG photos) and zero minutes of voice calling. And that's only available in 29 countries. Anywhere else you'll spend two cents per kilobyte, which means that it would cost $.75 just to read the international roaming rules on AT&T's website (the page is 37,446 bytes).
The upside: International plans can usually be added and removed without affecting your long-term contract.
The downside: High rates can still apply. Some international plans, like AT&T's iPhone international plan, are an addition to—not a replacement for—your regular service.
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Rent a phone
If your mobile phone isn't GSM, you can rent during your trip in many places. Try checking the airport website for your destination; many have kiosks where you can pick one up when you disembark. Or check travelcell.com for locations.
The Upside: The convenience of one-stop shopping for phone and minutes in a location where you can dump them off when you leave.
The Downside: Renting a phone (even before you buy minutes) can actually be more expensive than buying a cheap cellular phone abroad.
Buy a SIM chip
If you have a GSM (tri- or quad-band) phone, ask your service provider to unlock it. You can then swap out the SIM card—the plastic chip that gives a GSM mobile phone its number—for a foreign SIM card. Buy one from companies like Cellular Abroad (cellularabroad.com), or at a newsstand when you arrive. Rates start at about $20, plus pre-paid minutes (generally around 20 cents per minute to the U.S.). If you're country-hopping and don't expect to make lots of calls, pick up a global SIM card; cards and rates are more expensive—around 50 cents per minute—but you'll keep the same number and won't have to buy a separate card for different countries. Incoming calls are generally free.
The Upside: Easy to find; since minutes are pre-paid, you won't get hit with mystery charges.
The Downside: You need a tri- or quad-band GSM phone, and most SIM-card sellers can't unlock the phone for you, or will charge you an "unlocking fee."
Stay away from the hotel phone
Remember that the phone is nothing more than a profit center for hotels. The exceptions: brands like JW Marriott, whose Wired for Business program operates over a VoIP and allows you to make unlimited domestic calls from the phone in your room and connect to the Internet for $10 a day. Unfortunately, until hotels around the world realize that gouging customers who use the phone will only drive guests away—and that they can't compete with the myriad calling options that now exist—using the hotel phone will rank among the fastest ways to fritter away your money. Just picking up the phone and dialing—even if you don't get connected—can cost a bundle. (I recently stayed at a hotel in the Poconos that charged $7.38 just to make a call, even when I didn't connect. And the hotel jammed cell phone signals on the grounds.) Ask your friends to call you.
The Upside: You'll avoid getting gouged.
The Downside: In remote areas where there's no cell service, or the service is jammed, you might not have a choice.
Make calls from your laptop
Voice Over Internet Protocol (VoIP) solutions like Skype skype.com or Vonage vonage.com route your calls via the Internet with merely a high-speed connection. You can make calls for just pennies per minute, receive forwarded calls from your U.S. mobile, have voicemail (included in the monthly $24.99 Vonage charge; $20 on top of the $60 annual Skype fee), and even purchase a number with your local area code for a low monthly fee.
The upside: Very inexpensive, easy to set up.
The downside: Requires a computer, an Internet connection, or even a special headset or handset; connections can make you sound like you're underwater; and some countries with state-run telecommunication and Internet-providing companies block VoIP.
Alex Segre / Alamy
Get an international number tied to your cell phone
A new service called Magellan (magnumbers.com) allows you to purchase an international phone number to link to your cell while traveling, so friends and family can contact you at their local rates. Get either a plan with a fixed monthly price or one with a local access number and a Magellan extension. Another service, Maxroam (maxroam.com), from Irish company Cubic Telecom, lets you accomplish the same thing by buying a SIM card for your unlocked GSM mobile and adding up to 50 numbers in 28 countries (for about $9.95 per number each per month). You can give out different numbers and accept all the calls on the same phone for about $42; roaming charges vary.
The upside: Magellan plans start at just $9.95 for an access number; your friends are charged only their own local rates. With Maxroam, your sound quality is likely to be very good, since you use a SIM card, rather than a phone service that re-routes your call several times.
The downside: Both services are better for expats and students than international travelers, since it costs others less to call you than it does for you to call home. And outbound calls can be pricey: using Magellan, for instance, an outbound call from your mobile number forwarded to Argentina costs 25 cents per minute. Also, both services are so new they don't have a track record yet.
Alex Segre / Alamy
Use an Internet air card
Turn your laptop into a cell phone: An air card is simply a PCMCIA card with a slot for your phone's SIM card. This way, you to get Internet service through cellular signals, even if there is no WiFi available. If your carrier supports air cards, you'll get both Internet and calling capabilities. Read more at sierrawireless.com.
The Upside: You can connect to your VoIP provider just about anywhere.
The Downside: Not all carriers support them, and international data and voice rates will likely apply.
Buy a phone with dual SIM capability
If swapping out SIM cards signifies just one more thing that you could misplace in your travels, consider buying a phone with dual SIM capability, which lets you keep two numbers in one phone and switch them whenever you want. The additional advantage: you won't lose the data on the number you're not using, such as missed calls, call times, or messages (which is possible when you take out your phone's SIM card). Or buy an adaptor for your single-SIM phone for about $15–$20. Find one at duosim.com or freeyourmobile.com.
The Upside: Lets you keep two numbers on the same phone.
The Downside: Some phones must be modified to use it.