You can be hit with surprise roaming fees overseas—even if your smartphone is turned off. Here’s how to avoid them.

Roaming Fees, telephone bill
Credit: Illustrated by Mark Matcho

The Federal Communications Commission says that one in six cell phone users has suffered “bill shock” from outrageous mobile fees. I was shocked, too—shocked that more people haven’t reported unexpected charges.

The horror stories I’ve heard come from travelers who have racked up hundreds of dollars or more in roaming fees—without having made or answered a single call.

Even more frustrating is being charged roaming fees when your phone is turned off. Philip Greenspun, a software developer from Boston, discovered this the hard way after a trip to the Bahamas. Except for checking to see if he had a signal a couple of times, he left his phone off and didn’t make or receive any calls. One thing he did receive, though, was a monthly T-Mobile statement with $144 in roaming charges.

“My first reaction was confusion,” says Greenspun, who holds a Ph.D. in computer science from MIT. “I hadn’t used my phone, so I knew something was wrong.”

Here’s how it happens: someone calls your cell phone while you’re overseas, and you choose not to answer. The call is routed from your carrier to the local telecom, which sends the unanswered call back to your local carrier. Your carrier charges you for forwarding the call, the local carrier charges to send it back, and you end up owing up to $4.99 per minute, depending on your location and carrier. Those charges apply even if the caller doesn’t leave a voice message. If he does leave a message, some carriers add an extra delivery fee.

Greenspun’s mistake was to have turned his phone on at all during the trip. By doing so, the local carrier automatically registered his device. The registration can last up to 24 hours, even if the phone is turned off. At that point, any calls to his number were subject to roaming fees.

Some cell phone providers offer travelers a refund in these cases—but there’s no guarantee that you’ll see the charges erased. In the meantime, the FCC has been soliciting comments about roaming fees, though a spokesperson told me recently, “We have no specific timetable on bill-shock action.” In other words, don’t expect government help anytime soon. For now, when you roam, you roam alone.

Activate your phone’s Unconditional Call Forwarding setting, which prevents incoming calls but allows outgoing ones.

Forward calls from your cell phone to a voice mailbox not associated with your mobile, then check messages using a landline.

Set your phone to Airplane mode; you can access Wi-Fi, but your phone won’t register with the local carrier.

Sign up for a temporary or monthly international phone and/or data plan.