I answered the call by saying nothing, after about 30 seconds the caller hung up.
Its a robo call that waits for a voice, if you say nothing it does nothing.
A real person would say something when the call is answered.
I am so sick of these calls, too, but I have a VOICE caller I.D. and when I do not recognize the call, it can ring forever as far as I am concerned. I think the telephone companies are just as responsible for letting the scammers use all of these telephone numbers to harass people.