I would never stoop to the level of answering them so I have no clue who they are. I believe the people that do answer them are keeping them in business.
I have turned my answering machine off, who calls a landline anyway, only these [***] only that it comes with the package , I'd dump it in a heartbeat and this scum along with it. If I'm home if the rare recognized call comes in pick it up.. When you come home scroll the caller ID and call back the wanted call.
They NEVER get anyone or anything in this house that will EVER be answering them.....and guess what they never call more than tops 3 times before they get bored if it does go 4th time they get blocked......ah bien