T-Mobile’s new day pass option for international travelers makes it the most affordable option of the major U.S. wireless carriers. Additionally, T-Mobile has expanded its international coverage to an additional 70 countries and destinations.

“More than one in three families planning vacations this year intend to travel internationally, and Verizon and AT&T want you to pay twice as much every day when you travel abroad,” T-Mobile CEO John Legere says in a prepared statement. “With T-Mobile ONE, you just take your phone with you – turn it on as usual and it works – no worrying over your wireless bill, just enjoy your family time and see the sights.”

T-Mobile’s international plan, T-Mobile ONE, is now available in over 210 countries and destinations, providing customers with unlimited data and texting. For an additional $5 per day, however—about half the price of comparable plans from Verizon and AT&T—T-Mobile subscribers gain access to high-speed data and and unlimited calling while abroad.

This is a good deal. As some readers may know, I’ve stuck with Google’s Project Fi for a few reasons, but the most important is that international data is charged at exactly the same rate as normal data ($10 per 1 GB). And because Project Fi now caps subscribers’ monthly bills at $60 in any given month, I’ll never pay more than $60 per month for data, no matter how much I use or where I am in the world at the time.

T-Mobile obviously isn’t match that deal, and that high-speed data it offers is capped at 512 MB per day (where Project Fi is unlimited). But T-Mobile has at least one relevant and major advantage over Project Fi: It works with virtually any smartphone, whereas Project Fi is still limited to a handful of Google and third-party phones. And for people who don’t travel internationally all that much—e.g. most people—it’s obviously a better deal regardless.

So this is interesting timing, as I’m heading off on my first international trip of the year this Friday for our annual home swap. We’ll be gone for three weeks, so the most this trip can cost, from a cellular phone perspective, is about $100 ($30 for texting, plus the $60 cap for data), including taxes and fees. (And not including phone calls.) On T-Mobile, the international day pass alone would cost about $105, plus whatever the normal monthly cost is for the cellular plan.

Looking past this trip, I try to spend about a month outside the United States every year, and I do have about 9 more days of international travel scheduled for the fall already. So you can see why I cling to Project Fi. But this T-Mobile deal has me thinking. And I could see making a break.

Anyway, I’ll be writing a lot more about this and other travel-related issues over the next few weeks for Premium members. Stay tuned.