IRS scammers trying to threaten you with a lawsuit.  DO NOT GIVE THEM ANY INFO.  They ask for your name and information and try and scare you with threats of a lawsuit.  The IRS DOES NOT call, they send certified letters that you sign for

Robocall - this should be a dead giveaway that its a scam!

Didn't pick the call and blocked the number

yeah, what a bunch of scamming bags of ______ (fill in the blank).
First - the IRS will send you letters.  Period.  that's how they do it.
2nd - they would not have a fake computer generated "this is the I R S" robocall...
And if you DO call them back, you're not going to get some over-seas operator from India or wherever.  The IRS does NOT farm out or offshore their collections or investigations group.
They are lying scum bags.