Good heavens, David, DON'T return the call. It is a SCAM. A well known scam. The IRS has been warning people about it for years. Read here:
https://www.irs.gov/uac/newsroom/irs-repeats-warning-about-phone-scams
http://www.forbes.com/sites/johnwasik/2016/06 ... u/#6cb8a18e171f
Never answer calls from numbers you don't recognize or persons you don't know. Again, this is a SCAM. Do not engage these thieves.