Well where I live, if someone said that to you it could be grounds for a discrimination lawsuit under ADA. But it's very difficult to find a lawyer to file a "refusal to hire" lawsuit on your behalf because they are so difficult to win, and in my state you can't record a phone call or conversation without both party's consent. In any case, I recently got a job where I have to speak on the phone frequently. I've gotten a lot better at it after a lot of practice. I work in an open office which is even worse because everyone else can hear me. It was really bad at the beginning, but after a while it's gotten better. Practice helps. Just start making calls to random businesses asking simple questions like what their hours are or whatever. It will help a little. Good luck my friend.