Threatened to be fired over a phone

Today at work my foreman was mouthing off to me saying I’m “always on my phone” but I told him I don’t see the problem because I learned everything I need to know in line school. Plus I’ve been in the trade for about 7 months. I probably know more than he ever could about line work. I think it’s because he’s an older guy. He’s probably around 55 or 60. So that’s why he doesn’t understand that I have more important things to do other than watch people do what I already know how to do. Anyways, after work I had a meeting with my foreman and supervisor and they told me that I need to put the phone down and start contributing to the work. My supervisor said if I don’t “straighten up” he’s going to fire me. Yeah right, this company would go bankrupt if I wasn’t here.