Like @bentdouble already said, I think the unknown anticipation on the other caller’s end is what makes it so stressful. “What is the person thinking when there’s a long pause?” I know that too well. But in the end, it goes back to the Stoic philosophy. Control what you can control, accept what you can’t. You can’t change your stutter, or rather THAT you stutter, but you can change the way you deal with it. You cannot change what others MIGHT think. Oftentimes, it’s worse in our own head than it is in reality. So don’t take it too hard on yourself. There are things way worse in life.