Thanks for the info.  Obviously, the IRS will NEVER just call you out of the blue.  They will send you a letter first.  Or, if you've been really naughty, they will show up at your place of business or home with a search warrant.

They say they are the IRS and give you a case number telling you that there will be a warrant for your arrest and a lien placed against your bank accounts and your home.  They say you owe money and can be quite rude and forceful when they talk to you.  

this guy with an indian accent called and said he was with IRS and he had a warrant for my arrest.I told him he was full of [***] and he got real nasty but he hung up when I said I knew he is an obvious fake. I called the number back and they answered "this is the IRS" but when I asked to speak to their superior they hung up.Theses guys are real jerk-[***] criminals and they are definitely NOT IRS

I just got a call at 8 am!

Federally mandated calling hours for Telemarketers,  debt collects,  etc.   are  8am - 9pm your local time.
Criminals/scammers  set their own hours.