The callers are the drug-addicted "card services" scammers, who call us, pretending to be associated with our credit card companies, in an attempt to fool us into giving them our credit card numbers, so they can rip us off. People that have given their card numbers to these junkies have suffered severe financial losses. Beware of these lowlifes, and warn others, before they are cheated!
As you say, not answering the calls of the "card services" scammers is a good idea--for those of us fortunate enough to be able to afford the extra expense of caller id. Many of the "card services" scammer's main targets, the low income and the elderly, are not able to afford this luxury, and that is a reason the scam has continued for years, and remains profitable for these degenerates. All of us who are aware of these lowlifes, need to inform others of the scam, and then ALL of us will be the beneficiaries, when the calls become unprofitable, and stop.