I'm sorry that person did that to you, Eve. That person needs to take a step back if s/he is getting upset by normal human behaviors. Most who are called cannot or don't wish to volunteer and that is fine. It's not for everyone.
I phone bank when I can. Due to my knee & foot problems, I cannot canvas yet. I've never had anyone scream at me. They ones who aren't supporters typically hang up.
For phone banking, we are given a campaign cell phone (so they can keep track of the cost) and a list of likely Dem voters who have either voted dem in the past, or registered Dem. We don't cold-call anyone, nor do we call anyone who has registered as a Republican. So it's rare to have someone on the other end of the line be hostile.
It was intimidating at first but after a few calls I got to meet a lot of wonderful, like-minded people in my deeply red community. Many of them have become friends over the years. It also helped me see that I am not alone. It also helped me build self-confidence. But I didn't ever volunteer until I felt I was ready, and some people just don't like the phone and that's ok.
I will admit that as the election draws closer I have trouble maintaining my affect with friends who are Trump supporters. I'm not sure I can even call them friends anyone since I have a problem with anyone supporting a rapist.