I have a mild stutter and yes my stutter is more noticeable while talking over the phone but it’s mostly due to nerves. I figure that once I’m comfortable and accustomed to talking over the phone to customers, my stutter will not be too noticeable. And I’m not one to shy away from talking due to my impediment. I think constantly talking will actually improve my speech. My stutter isn’t severe but ever I ever hope to be get rid of my stutter, constantly talking and stepping outside of my comfort zone is the best way to go.