My various bosses have given me grief over the years because of my attitude about phones (I hate them!). They feeeeeeeeeeeeel that I am being disrespectful because I have rules regarding my phone and I enforce them with rigor.
I don't answer the phone if I don't know the number on the display or if it reads "private". If they don't want me to know who they are I don't, either.
One of my bosses once axed me why I won't answer and I told him, "After my x killed our daughter she went insane and I don't have any interest in dealing with her that doesn't involve a .357 and a shovel"
When I give out my number I tell my customers, "Call me if you need me - but abuse the privilege and I'll block you and you'll have to look elsewhere for support". Only one guy found out I was serious and he was dogged by everyone else, telling him, "You F it up for us and we'll F you up for good measure!"
Understand that telephones are for business and not sorting out your feelings. Start that with me and you'll hear a dial-tone.