Fake IRS scammer calling to fool and commit fraud by telling random people they owe money/have a warrent/can go to jail. Answer and ask them to call right back then act innocent or scared while Recording them on speakerphone call with a handheld recorder or old phone with memo recording ability (iPhones have them). This can be used for proof of fraud and identifying the people doing this by emailing to police. Vigilance prevents more from being scammed- which are often vulnerable seniors.