Home Phone can look like its working but it's not

I had contacted support but all they did was instruct me how to reset it (as if I didn't know that already).

I'm going to keep a log of trying make outgoing calls once per week, to start with, to hopefully get an idea of how stable it actually is.

The device is only 10 feet or so from a window but our house is on a hill and the room is on the uphill side. Because it uses a cellular connection, I'm going to move it to the downhill side (that faces the valley) and closer to a window to see if that helps.