Is it normal, that i'm too scared to talk to her on the phone?

I have telephone phobia and I have had it for a few years. I'm not quite sure when the fear developed exactly nor the reason why it formed. Regardless, it has made certain situations in my life very difficult. A few months ago, I started seeing this therapist and among other things, one of the things I am seeing her for is my long list of phobias.

I noticed sometime after my third or second appointment with her that she was subtlety trying to nudge me into being able to talk to her on the phone. The more I thought about this the more my panic started to set in. When I first tried to make an appointment with her I tried calling her. I was so scared that I had this "music boosting confidence" ritual where in which I would play certain songs while I was on the phone because, I thought that it would help to ease my nerves, though it never did. Anyway, she never picked up, much to my relief. I found out a few weeks later that she had been out of town.
She has called my phone once but, I thankfully did not answer it because I was half asleep.

The main reason I am scared to talk to her on the phone is because I am terrified as to what her voice will sound like. In person she has a very nice voice, but in my experience the phone has the ability to warp the way a person's voice sounds. The warped effect has caused me to feel a variety of emotions from shock and surprise to even annoyance. What if I call her at the wrong time and her voice ends up sounding angry? I don't think I could handle that.

I also fear the dreaded awkward silences or that I might end up saying something stupid. Or, what if I accidentally say something that she misinterprets as being offensive? I want to talk to her about this but I keep forgetting to bring it up during sessions. When I do consider telling her this, I usually change my mind because the thought of talking about this embarrasses me. IIN?!