Is it worth buying an unlocked phone?

A phone purchase now looks less phony, courtesy of a spike in sales of smartphones that don’t come locked to a wireless service. That should be good news — unless you like preinstalled bloatware and punitive international-roaming charges.

The market-research firm NPD Group reported Monday that unlocked phones make up 12% of the U.S. market. That represents a remarkable turnaround. Until 2013, carrier pricing punished shoppers who brought their own devices instead of buying them from the service — and locked to it — at prices subsidized by higher service fees.

T-Mobile’s groundbreaking move to dump phone subsidies and their two-year contracts has since pushed AT&T, Sprint and Verizon Wireless to do likewise.

“Unlocked phone adoption began growing in the last 18 months or so,” NPD analyst Brad Akyuz wrote in an e-mail. He credited increased online phone shopping (NPD’s tracking of purchases found that 51% of unlocked phones were bought online) and such Apple direct-to-customer retail options as the iPhone Upgrade Program.

NPD found that 35% of unlocked phones ran iOS, vs. 65% for Google’s Android.

Among unlocked Android phones, Akyuz and analysts Jan Dawson of Jackdaw Research and Carolina Milanesi of Creative Strategies separately pointed to Blu Products, which sells unlocked phones only on Amazon — some reserved for Amazon Prime subscribers at prices subsidized by lock-screen ads.

Akyuz also noted the popularity of cheaper prepaid wireless services that often don’t sell highend devices. Using an iPhone or a Google Pixel with them may demand buying it yourself. “We are seeing unlocked prepaid device adoption hitting as high as 25% depending on the carrier,” Akyuz said.

The benefits of unlocked phones extend beyond a wider selection and cheaper choices. They also liberate you to switch carriers at will — and buy cheap prepaid service for international travel instead of paying costlier roaming fees.

Unlocked Android phones also ship without the extra apps carriers preload, and which you usually can’t remove. And Android updates should arrive a little faster without carriers subjecting those patches to their own tests before sending them to phones.

The traditional downside of unlocked phones has been giving up a carrier’s installment-plan financing — as Milanesi said, they make “consumers realize the real price of phones.” But with Apple and now Google offering interestfree installment-plan payments on their own unlocked phones, that reason is going away, too.

“We are seeing unlocked prepaid device adoption hitting as high as 25% depending on the carrier.” Brad Akyuz, NPD analyst