I notice that several people mentioned they are on the national do-not-call list. I did put myself on this list, because anyone can get a copy of this list just by asking for it. That should be obvious; if the list wasn't freely available to everyone, it would be useless. My point is that scammers can get this list just as easily as legitimate companies. Then the scammers have a list of tens of thousands (maybe hundreds of thousands) of phone numbers that they know are current. They don't care if you try to report them. They will never give you any real information about themselves, so you have nobody to report. And even if someone somehow tracked them down, it would take months or years for the government to do anything about it. In the extremely unlikely event that they got shut down, they would just open up in a couple of days under a new name with new phone numbers. There's no way I'm putting my name on that list.
They left no name on my caller ID and no message on my answering machine. So this is either spam, telemarketer or low life or all 3. I wish they would shoot thees jerks.
Do an internet search under "card services FTC." Every year these call centers pop up and it takes the FTC awhile to shut them down but they can not do it without complaints from recepients of the calls. They ignore the Do Not Call List and all telemarketing rules; I suspect they are shady. Go to FTC.gov and report them. While on the website, make sure your number is on the Federal Do Not Call List. It does stop LEGITIMATE telemarketers from calling (but there are loop holes with that too). Good Luck.