What’s “data roaming?” Lisa was under the impression that it meant roughly the same thing as voice roaming: using up one’s data allotment while in an area outside of your carrier’s coverage. The phone will indicate when you’re roaming so you don’t rack up expensive roaming minutes or megabytes. Except that’s not how it works: Lisa’s phone just roamed invisibly. Her mother’s apartment is in a previously undisclosed T-Mobile black hole, and she ran out of data while traveling.

I visited my mom in the SF Bay Area in July. I have an Android that I use habitually, so before leaving I checked if she lived in a covered area (T-Mobile’s data coverage map has her in a “Very Strong” area surrounded by “Excellent” with no gaps) and, just to be sure, I went into my phone settings and unchecked “Data Roaming: Connect to data services when roaming.” (Mostly, I was worried about automatic data use during the drive down.) For the record, I have their $10/mo Unlimited* 2GB plan, which comes with 50MB of roaming data. T-Mobile also has a 5GB plan with unlimited roaming for $25/mo.

On 07/27, I received a text message: “You’ve used up 40MB of 50MB allotted for data roaming. You will be limited to 50MB.” I called T-Mobile, confused, and the representative told me that “I don’t see this on your account” and “this is probably just a system error.” So for the next day, I kept using my data plan. (And I stayed at the apartment because of the Olympics, so I couldn’t have left the service area.)

On 07/28 I got a text informing me that I had reached my limit. The web stopped working. I called customer service again and the rep told me that in order to keep using data, I would need to upgrade to the 5GB plan. I told her I didn’t want it and that, had I known I would be roaming, I would have been more careful. Besides, I was going home again in three days.

I asked why I was roaming in the first place if the setting on my phone was off. Here’s the kicker: the Data Roaming option only controls whether or not you roam while traveling internationally. What T-Mobile calls Data Roaming is not what my phone calls Data Roaming. I asked if there was an option to turn off accidental data roaming while in-country. She suggested I turn off my phone. But aside from a supposedly erroneous text message, I had no reason to believe I was roaming, so why would I have done that?

Check your phone’s manual (or user forums) to find out whether there’s a way to disable mobile data when you don’t need it, especially if the phone has wifi access.

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