There was a time when I was really anxious to talk to someone on phone. So, I took up a challenge named "100 days 100 people" in which I would talk to people from all walks of life whether man, woman, old or a kid on phone. I would at least talk 1 person per day. I was using the app called Goodnight app (if you were interested to know). This has led me to overcome my anxiety. Today I am confident to talk to anyone on call.