Don't waste your time getting a Signal Booster. After 2 months of trying to connect the Signal Booster/Cell Spot device, I finally got a Tech that knew what he was doing; an American.
Go to your phone settings. (Android, Samsung A50)
Set to Wi-fi calling, click on the actual word "Wi-fi Calling "
Click on Calling Preference, click on
You're all Set! No Signal Booster Needed.
Why doesn't T-Mobile tell everyone this???
I could cuss...