I notice that when I give myself time to rehearse, I stutter more. When I rehearse and breathe more before someone picks up as the phone rings I stutter like I’ve never stuttered before. Full on, out of breath, “what tf is wrong with me?” Stuttering. If I don’t think about it or plan a course of action thru my chosen phrase, and just act aloof before it’s my turn to speak I am more natural in my fluency. I’d like to think people who don’t have a stutter don’t practice their whole conversation mentally before the line stops ringing, and since then it helps a bit. Oh and my number one trick is to speak with it on speaker phone when I’m home. Idk but it’s like I can breathe better and don’t get blocked up if the phone seems louder than me.