For the longest time, I had difficulties using the phone because of anxiety. I felt on the verge of a panic attack whenever the phone rang and I knew I have to pick up the receiver, even when I knew it was an old friend or a relative and the conversation wouldn't be about anything significant, so there was absolutely nothing to fear. After a while, the anxiety would subside and it'd become easier to talk, but the beginning of the conversation was almost invariably awful. It's also much more difficult to adjust to the timing of the conversation on the phone (because I can't see the face of the person I'm talking to, or their gestures, and can't pick up any nonverbal cues that could provide some indication), so I could rarely tell when was my turn to speak. I'd end up interrupting, talking over the other person, failing to say what I wanted because I had missed my turn, or sometimes the two of us would start saying something at the same time, then fall silent, then start saying something again, until one of us decided to keep quiet and let the other do the talking (this used to happen and still happens to me in ordinary conversation as well, but on the phone it could be far more frequent). The anxiety only made things worse, of course.
As a result of all this, I ended up absolutely *hating* talking on the phone. I've become better at it recently, and can keep up a more or less smooth conversation (at least when I make an effort to stay calm and don't let the anxiety take over again), but I still prefer either email/text messaging or meeting my friends in person.