the number that displays tracks back to a civic organization in St. Cloud, MN which probably has nothing to do with these scumpuppets. The phone company needs to do something about these people's ability to spoof the caller ID to display a different number.
I just hit one now, wait for them to come on the line, and scream as loudly as I can - if you don't have the voice for it, keep a referee's whistle next to the phone. send them home from work with a bleeding eardrum. I don't have a credit card, they don't have the ability to hear out of one ear.
These are literally CRIMINALS who are phishing for credit card numbers. They are faking their caller ID. The FTC is working on nabbing them. Talking to them or asking them to stop calling is pointless (if anything it will get you put on a 'live person' list so you will receive even more calls). If you feel compelled to fight back, pretend to be genuinely interested but give them fake credit card numbers to pollute their list.
Criminals like these would be much easier to track down if it was harder to fake the caller ID. Search for the "truth in caller ID" act of 2010 to learn more.