It is likely a scam. You can check casenet to see whether a lawsuit has been filed. Sounds like many FDCPA violations, but I question whether you'd be able to track down who called.
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Contact your state government. Most states have departments to deal with unlicensed debt collectors or collectors that are violating state & federal law. Often these departments are part of the Attorney General's office or are within the State department of business. The state telephone operator will connect you to the right department - all you need to do is call the state hotline. Hope this perspective helps!
These sorts of calls have gotten very common in the last few months. I recall that a couple of years ago some payday loan company was hacked and information stolen. That may be how these "collectors" got your name and information. I agree that they are most likely scammers, but short of letting the Attorney General of your state know about it, there is little to do. These scammers are difficult to serve with FDCPA complaints and regularly ignore judgments against them.