Unless they provide you with writtten proof of debt per the FDCPA they are more than likely a fraudulent scam.

I got a call from this # - I called back and they said they were the "UMA" corporation and gave me another call back # of 877-643-6608.  A quick google search reveals that this is a company called United Management Associates and they are a debt collector.  Apparently they're trying to collect a debt from someone that lived in my home and/or had my # before.