Here is a twist I have not experienced before when researching unwanted numbers. I entered this number in the URL bar, where your website location is listed "http://www..." Instead of giving me a bunch of Google hits as it usually does, it gave me a page with all my connection information, modem information, and my local network info. This includes my email address and my IP addresses. Have I unwittingly sent my computer info and other things to these people?
Called left no msg. I do not answer if I do not recognize the number and if they don't leave a msg then I don't call back. It's nuisance but I ignore it. I would never give out information regarding any credit card or personal information to anyone on the phone I don't care who's calling and you shouldn't either. This is how some people get scam. If you think it pertains to you ask them to send it in writing that you don't give information over the phone. If they insist hang up!