Like others, I too have a dislike of making phone calls tbh. I do it, obviously, because sometimes you have to!
I've never really thought too much about the 'why' of it. I'd kind of assumed it's to do with my natural shyness but upon reflection I realise that I actually find the conversation a little unsettling because I can't see the person I'm talking to. Like I'm talking to nobody. Maybe I need the reassurance of seeing facial expressions etc? Dunno. I think maybe I even become a different person on the phone, as I either tend to gabble a bit or go entirely the opposite direction and become monosyllabic and overly functional. I'm certainly not relaxed on the phone, let's put it that way!