I definitely prefer email. It's so much easier to get a full understanding of what the other person has said by reading it over and over, and you have as much time as you want to reply, so those confusing conversational rhythms aren't an issue.
However, I don't mind, and often quite like talking on the phone to someone if I'm the one being called. I feel like it puts me in the position of power. Where I get to go, "oh, hello, who is this? Explain yourself? What is your business?" even if I've looked at the caller ID. The only annoying thing is that I apparently have a very feminine voice, and am constantly mistaken for the male occupants of the house. Also, sometimes - almost always - the person on the other end of the line simply doesn't respond. They used to not hear my "hello," so now I wait a moment after accepting the call/ picking up the phone before I say it. Other times, there is always an awkward pause, because I'm hardly ever the one they're after, and they don't recognise the voice. Most of the time though, they just ask if my parents are there, but the mum of one of my little sister's friends one time just went, "hello! Helen!" as if she was at the front door, not talking on the phone, and as if she didn't realise that, with 5 people in the house, there was an 80% chance that it would not be "HELEN!" on the other end of the line.
When I'm the one calling someone else, though, it's very scary. I can't bear the sound of that mechanical ring that could any moment be interrupted by the voice of an oblivious person to whom I have to seem purposeful. The only people I can confidently call are my family and my Aspie friend. I can call other people, but not without getting a panic attack. I actually prefer more business-like calls though, but when I'm a customer. I think of the formality as something safe and structured to hide behind, as long as its a typical call. I haven't really tried to get a job yet, but I imagine it must be very nerve-racking, for the reasons that many of the people on this thread have already outlined.