There's nothing rude about it, the breathing thing is about slowing down. The problem is, is you're probably thinking about 1000 different things at once... all that is doing is scrambling your brain making it impossible to get the words out. Just slow down, try to be calm and positive. Even if you do stutter, that isnt a problem. You need to be easier on yourself, dont expect perfection just try to remain calm. I know its hard, I used to hate phonecalls too. I didnt even own a phone thats how bad I was. Just sharing what things helped me