You get comfortable about being uncomfortable and you push through. If you have to present, then practice every single day. If you have to use the phone, buy one off of Ebay and practice every single day making and receiving phone calls. Practice DOESN'T make perfect, practice MAKES permanent. If you don't face your fears head on, they will dictate every facet of your life. We all have that courage within us, find it and you'll be unstoppable. (BTW, I'm a National Trainer presenting every week to hundreds of medical professionals: doctors, nurses, social workers, etc.)