Same as others have reported. When a caller refuses to leave a message, I am increasingly treating such calls as scam / unwanted solicitation calls. I enter every such call into my contact list, so that they get even less of my attention next time they attempt to call.
I pick up phone and say hello and lay the phone on the radio so they can listen to Rush Limbaugh, Sean Hannity or whoever is on. If I pick up phone in different room I bang it on the door or desk so they can listen to that and I can't hear them. It says GAD on ID.