Can you "lock" an unlocked phone?

There are software features available on locked at&t phones that don't work on unlocked devices.   Specifically, numbersync was an important feature linking  my at&t samsung phone with my samsung smartwatch.   My new samsung phone, an A50 purchased directly from Samsung, won't allow me to pick up calls to my phone on the LTE - enabled watch unless the 2 devices are connected by bluetooth.   Can this be fixed by locking the phone somehow to at&t?