I didn't recognize number so I didn't answer.  Actually the number that came up on my caller ID was 279-000-1555.  Their call back number was 727-900-0155.   They did leave voice mail, saying they were the IRS, and had a warrant out for me.  Well, 1) IRS doesn't make phone calls, they MAIL you.  Frigging scammers...they blocked now.

Claimed to be the IRS.

IRS scam

Scammer is now modifying caller ID to display +7 (279) 000-15-5.
I've blocked previous numbers which stated that "it is a matter of legal importance".   They've upped it now to that I'm "being physically monitored".
I'm filing a complaint the IRS Enforcement.

I'm being physically monitored by the IRS and I needed to return their call although I answered the initial call.