OK my problem is that I can't stand calling girls. I sit around forever before I call them with my finger on the send button but I usually chicken out 10 times before I actually call them, then after that I'm not nervous at all. Now this may seem just like general shyness, but I have no trouble just walking up to girls and talking to them, or even asking them out.

Even when the girl makes it obvious that she wants me to call her, I'm a nervous wreck right up until the moment I press send.
Any advice or opinions on this?