Caller left message with something to the effect of: "This is Jonathan Smith with the investigative department of the IRS. There is an arrest warrant on your name, and your physical address is under federal investigation. Before anything goes wrong, call me back at 347-797-5210. Have a good day."
Research shows that the IRS typically sends letters if there are real issues. http://www.irs.gov/uac/Newsroom/Phone-Scams-C ... 5-Filing-Season