Communication Channels

I'm truly curious here so please, clarify if you can.

I read so much about "they don't pay for your cell phone" don't answer it or text back etc etc.

Clearly, if you're still in your probationary period these suggestions might not be an optimal approach.

Once out of your probation, is face to face and your scanner the only communication that you are required to respond to?

Am I missing anything here?