How to overcome phone shyness..

Call someone you’re comfortable speaking to on the phone first. Right before you have to call a stranger/someone who makes you nervous, call someone up like a family member or significant other that you feel completely comfortable talking to over the phone. After a short chat with them, immediately make the other call.

This is a very effective technique for calming your phone shyness, as the first call soothes the part of your brain that associates being on the phone with stress.