Sounds like an utter asshole with uptight ignorance. You're better off moving on! Why work for a company who clearly isn't willing to be patient and able to value you more than just your stutter alone? As someone who recently got offered a job and starting next month (I also would be expected to answer phone calls), I told my interviewer in advance of my stutter before the interview so they don't associate it as anxiety. They reassured me it won't be an issue to the role so I can only wait and see how I feel next month. It's so important to be with an employer who can admire your courage and bravery to not let your stutter hold you back. Don't let other people's problems about your stutter be your problem, they're the ones who should deal with it. I'm sure you can offer much more to the *right* employer.