I understand your situation bro, I hate talking to people on the phone especially these official conversations. It takes so much of energy to talk with stutter in everyday conversations but in phone it requires double the energy. Also the feeling of embarassment is always in my mind. On the other side I hope that you get your work done. Think of it as practice. My speech therapist used to tell me to talk to everyone on the phone. It might help to reduce your anxiety. It may or may not help but remember you are not alone in this. We all are with u.