Try not to dwell at all on your stutter. Focus on the message, what you want to say, the answers to questions, etc, don't even give the stutter a second thought. I know it's easier said than done but we also know dwelling on it just makes it worse anyway so why waste your time. May as well focus on what's important. Don't link your stutter to this phone conversation in your head before it's even happened. Just focus on what you know you can control, kindness and friendly attitude, answers to questions, etc. It's just another thing. But what helped me a lot was to set my mind beyond my stutter. Think past it and don't even give it the time of day. ​ If you still feel nervous before the conversation you can take a nice breath out, nice breathing not for the sake of your stutter but just to calm yourself because the goal is not to think about the stutter at all. Keep focusing on what you want to say, the whole message, how you want to answer the whole question from start to finish. It helped me immensely not to jump right in anxious to answer anything until I had my whole train of thought and how I actually wanted to answer a question already in mind, all of it and not just how I wanted to quickly start, if that makes sense (we fall into this pitfall because we're more worried about stuttering than the question at hand so we're anxious to just start before even deciding on the answer). As I was thinking about the whole question and what my answer will be, I began forgetting about my stutter ironically. Worrying about the stutter is a waste of time in essence. The deeper I thought about the answers, the more it overrode my stutter. It got to the point where the moment I even thought about my stutter I would say "Bah" in my own head and refocused on what I was supposed to be thinking about. And then that became second nature over time and took all the undo stress I used to put on myself out of the picture. But it took practice, I had to do it consistently in small situations and big, it was all the same, I would not allow the thought or worry of my stutter to have free rent in my mind any longer. Not before, not during, and certainly not after. So what ever happens happens, I would not dwell on it!