dont knows calling me?

Free credit report dot com is Experian. The debt could be on a credit report maintained by TransUnion or Equifax. Use the Federal Trade Commission's free service to obtain a copy of all 3 of your credit reports annualcreditreport.com

You can also Google the phone number, find out who it is, then send a DV request via the mail.

Are you sure it's actually telling you that you owe something and not a solicitation in disguise? I believe it is illegal to leave details like that on an answering machine.

I know I get an automated message all the time that when you first hear it sounds like Oh crap, I have a delinquent bill - but it is actually a credit counseling or settlement company trying to get you to call them to "work something out." They word it to try to get you to call them thinking they are calling about one of your cards when in reality they are just trying to get you to sign up with their program and they bought your name from a list just like any telemarketer.

Typically a collection agency will at the very least leave you a reference number on your machine so they can find you when you call back. Also, at least once a month - if not more, you'd get a message with a collector personally saying... hello, hello... because the dialer popped them through and it takes a minute to realize that no one is on the end and it's an answering machine. Not to mention, whatever collector is working that account would probably be going through manually every few days to make sure the account is getting a punch up. I think you'd get a live person at least once by now. Listen closely to what the message actually says next time you get it... it might not be what you think.