Amazon Prime ad supported phonesAmazon says its discount smartphones for Prime members supported by lock screen ads have been a huge hit, so the online retail giant is adding another unlocked Android phone to its stable of bargain devices.

The Motorola Moto G Play is the newest member of the program, and at $99.99 Prime members get $50 off the regular price of $149.99. Moto G Play joins the Moto G and BLU R1 HD, the first two phones with lock screen ads. Amazon said Tuesday these two phones are its best selling unlocked smartphones, which allow users to connect to the wireless carrier of their choice.

Amazon Prime box

Amazon earlier this summer announced plans to offer smartphones with personalized offers and ads on the lock screen. Amazon uses revenue from the lock screen ads to offset the cost of discounts.

“Unlocked phones are the fastest-growing category within cell phones on Amazon—and now our Prime exclusive phones are our best-selling unlocked phones,” said Laura Orvidas, vice president of consumer electronics for Amazon.

The phones use a single sign-on based on the Prime member’s existing Amazon account, with quick access to Amazon apps pre-installed on the phone. The phones also offer a selection of personalized daily deals via a new Android widget.

Amazon has gone all out with benefits to get people to join its $99-a-year Prime program. In addition to free two-day shipping on more than 30 million items, the subscription service offers free two-hour Prime Now delivery, the Prime Music streaming service, Prime Video streaming, the ability to borrow e-books through the Kindle Lending Library, and other benefits. The push seems to be working as a recent study showed that more than half of all Amazon customers in the U.S. have become Prime members.

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