Any job you want to be good at. I started stuttering at 10, got worse until 16, stayed the same until 20, started getting slightly better after that, and even better after 30. Today most of my work is buying or sales, a lot is on the phone or face to face at trade shows. It works out just fine, and gets better as I do more. When you stop caring about what people think of it, and work on technique because you want to, not because of what others think, it will become much much easier and you will become mostly fluent in 95% of the situations.