I have a request to make. If your phone rings and you answer it to dead air, please hang up.
That's what I do. I decline to stand there like a pathetic schmuck waiting for someone with an auto-dial phone in a "boiler room" to decide I'm the lucky "called" and get on the phone to try to get some of my time and (usually) some of my money.
I want you to hang up as well, in part for an arguably nasty twist on the ethics of Immanuel Kant's "Categorical Imperative," but mostly so that no mass caller with a possible legal hold on me — or you — can say that they'd made a good faith effort to contact people if they only call with auto-dial phones — or, come to think of it, send out junk-mail notices.
First-class mail, real person making real call — OK. Some person in a (figurative) boiler room maybe not even in this hemisphere, putting calls out to the immediate world on a high-tech phone — nah. That's not a serious, good-faith effort to contact another human being. And there should be no "reasonable expectation" that people in boiler rooms making serial phone calls will actually get people to talk with them, or that people will open what looks like junk mail.