When I was a little kid I was really shy, which was easily explained away by the fact that I was a little kid. Now I'm nearly 17 and I have trouble functioning in situations that require any degree of socializing. I don't like to go into stores alone, and I have trouble talking to anyone that's not a really good friend or a complete stranger whose opinion of me doesn't really matter. Most recently my phobia seems to have expanded to talking on the telephone. Unless it's a parent or a telemarketer I'm completely terrified of answering, and more specifically, sustaining a conversation.

Lately this shyness/social anxiety has moved past odd personality quirk and into being really inconvenient. How do I go about fixing this?