Its good, to have management try to use our phones to contact us. If there was "strong language" about contacting us on our phones, they would make us leave them in our personal vehicles.
Gotta throw them a bone once in a while and answer the phone, so you protect your ability to carry it on car. But, there are things you can do to make contacting you as painful as possible. Act like you can't hear them, repeat something completely opposite to what they were saying and hang up. Later, when they text you act like you don't understand, then start playing text tag with them, arguing that's the exact opposite of what they just told you to do.
Rinse, repeat.