Carrier AT&T distributes the phones under the names Fusion Z, Motivate and Maestro Plus through its own stores and some retail chains like Walmart.
The model codes match those of three VinSmart models licensed by the U.S. Federal Communications Commission (FCC) to be sold in the U.S.
Their prices range from $39 to $89, including promotions and a two-year warranty.
All three 4G models have six-inch screens and operate on the Android 10 operating system.
Nikkei and Bloomberg had reported last October that VinSmart was partnering with AT&T to produce smartphones, with around two million units in the first batch.
VinSmart declined to comment on the reports.
The three phones are part of 10 smartphones models approved by the FCC, including Vsmart Aris, the latest mid-range model produced by VinSmart and is being sold in Vietnam.
VinSmart’s factory, located in Hoa Lac Hi-Tech Park in Hanoi, is capable of producing 125 million smart phone units annually.