I was the same for a long time. Until I took a job as an outbound telesales person. Nothing cures you faster than making 300+ calls to strangers every day. After that, I switched to inbound customer service which helped even more. Now when I need to make an appointment, enquiry etc, I just put on my 'phone voice' lol.

Obviously that isn't a practical solution though, but I thought I'd share details of my miraculous recovery from phoneophobia FWIW, I still hate private number calls. I just don't answer those cause I don't want to yell at telemarketers. Poor buggers.