Scam Collection Calls?

I received a call at work from a woman claiming to be calling from the State of Ohio IRS office asking where she can send a fax for tax levy. The number she called from was 412-921-5205, when I called it back the recording said "The number you dialed cannot be completed". Now this is not the first time debt collectors have called my jobb looking for former employees trying to collect on a debt, and I am wondering since the number this woman called from is fraudulent, my only guess is that it's a debt collector lying about who they really are. Any suggestions?