This is a SCAM.... They have called my cell several times and left an automated message stating that I need to call back regarding a  "Case File". I called the number back, and a guy with a thick middle eastern accent answered: Interbal Revenue Service.
I could hear lots of chatter in the background.
NEWSFLASH.... The IRS is an automated system, and a live person does not answer their phones.

Block this number!!!! Do Not fall prey to these CON ARTISTS!!