Ah - because they want to talk to vulnerable people - they are running scams and need to ensure the victims are caught off guard. So they call and say your car warranty is about to expire, your child is in lockup and you need to send money for bail, that the IRS is performing a collection and you need to pay off in gift cards or you will be put into jail.
Those all sound stupid and who would fall for them? People with dementia or other cognitive problems. That's why the scammers need to place so many calls and do so rapidly, because the victims are such a small percentage of the general population. Often they pick numbers for the Caller ID with the same zip code so it might appear to be someone local. They know many people have phones set to ignore "Unknown" so they sometimes pick real numbers so that any service that is blocking calls will compare and see it's a legit number; the service cannot tell where the call originated but the telco can and they don't care.
It's why they don't leave a message and waste no time with answering machines. Their scam doesn't work if the person realizes they don't have a car warranty, calls their child to see if they are OK, and thinks about why the IRS would not have sent an agent to the house if the situation was that bad - or call a lawyer or friend for advice about it.
It certainly sucks to be on the receiving end. The FCC could do something, but that requires pressure on all the telcos. It only takes one to accept this garbage and the rest of the telcos have a far harder job (and if they do it, they lose the pass-through fees so they don't want to.)
