I did not pick up, but the voice mail said IRS is filing a law suit against me, which is clearly a scam. Don't believe this!

The IRS reminds people that they can know pretty easily when a supposed IRS caller is a fake. Here are five things the scammers often do but the IRS will not do. Any one of these five things is a tell-tale sign of a scam. The IRS will never:
Call to demand immediate payment, nor will we call about taxes owed without first having mailed you a bill..

Demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe.

Require you to use a specific payment method for your taxes, such as a prepaid debit card.

Ask for credit or debit card numbers over the phone.

Threaten to bring in local police or other law-enforcement groups to have you arrested for not paying.

I got a robotic male voice on my cell saying it was "calling to inform me that the IRS was filing a lawsuit against me". It called from the same number that it left for callback "for me to get more information". I chuckled when it mispronounced the word "information", leaving out the R. I did not call back. Blocked.

I received a robot voice mail saying to call 484-507-9536 that someone has filed a lawsuit against me and to find out more information to call them back at this number.

Same, exact  thing happened to me.