First off, it will get easier. If phone calls are one of the situations you avoid, you can practice talking to people on the app wakie or by calling stores, etc. It's OK to stutter, a lot of people are not perfectly fluent, especially on the phone. So, go in with a positive attitude and be prepared to grow. I think you'll find that talking on the phone gets easier and easier the more you do it. Remember not to be so hard on yourself.