Honestly, every time I need to make a formal phone conversation with someone, I get nervous, like very nervous. I feel like I'm being interviewed by a stranger sometimes. I hate the fact where your impression when the other person's talking is depending on the voice only. Even though we still can get the contents from their language and intonation, I prefer it to be a face to face conversation. Why? Because at least when I'm saying something to you face to face, I can see your reactions towards the message. I can know whether the message is delivered successfully or not, and I can know (maybe not every time) if the thing that I said is affecting you. When on phone, who knows maybe the informations are missed, I misheard something, got the wrong info etc. etc.
Due to all of the above reasons, I prefer to communicate through e-mail whenever formal matters are concerned. I'm not confident having a phone call thus I'm avoiding it as much as I can, but I still have to deal with it though, I know. I'm working on it now, to be braver in future, considering on my future working environment where more formal phone calls are needed.
I remember I was so nervous making a phone call to Astro Customer Service to upgrade our package at home. I kept telling myself "just do it, it's not like I'm going to die talking to that stranger on phone". Lol. So funny.
picture from Google