These people are calling on behalf of Chase, Capitol One, or others.
I answered one of these calls once. I asked them to tell me the credit card number they were calling about. They said they couldn't because of security concerns, to which I responded that because of MY security concerns I could not discuss a credit card account unless I knew the credit card number. I also asked for their first and last name and their direct call back number which they would not provide. Then, I concluded the conversation saying that I had would not discuss any credit card information from a caller who is not the credit card company/bank.