This number has called me over and over too. I do pick up and usually hear silence but when I picked up today, I finally got a voice. It was some sort of company asking if any renovations were needed for the house. I let them know I did all mine last year and was finished. The woman said 'oh, we're too late' and said goodbye. I'm hoping this ends those calls. Someone told me that these calls with the silence are due to some sort of mechanical dialing which dials about 10 numbers at a time and the first one that picks up is the one the caller talks to. The rest of the lines get silence when they pick up. Not sure if that is true but makes sense I guess.
It seems that talking to these tells them you are willing to entertain them and only increases the number of calls. When it comes right down to, no legitimate company would take a chance at violating the DNCR.