Budget US MVNO Unreal Mobile added AT&T to its list of operator partners, a move it said will allow more subscribers to switch to its service.

The brand launched in May, operating on Sprint’s CDMA network. Unreal Mobile general manager Samantha Lewe said in a statement more than 50,000 customers already transferred their existing phone to the MVNO. But she noted the deal with Sprint limited the pool of potential switchers who could bring their own device.

“Until today, only certain Sprint devices worked and most of those devices did not qualify [to switch]. That put us in the unfortunate position of having to turn customers away.”

Through the agreement with AT&T, Lewe said Unreal Mobile will now also be able to offer services to customers with GSM devices. Switchers will have the option to use an AT&T SIM with their current smartphone, or purchase a new device from the MNVO.

While MVNO arrangements are common, the partnership is notable as AT&T typically signs significantly fewer deals than rivals Sprint and T-Mobile US. Information compiled by AndroidCentral showed AT&T had a total of 16 active MVNO agreements in 2017, compared with 26 each at Sprint and T-Mobile.