Returned call stated it is IRS office and something about law suite. Told the call to send me it in writing . Caller said he already did. I told him to send it again but stated he could not. Then I hung up.

You protected yourself.  Good.

There is a fairly common IRS or "tax scam" being practiced by scammers in both Canada and the USA.
USA tax payers should read this:
http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
Note particularly the links at that site, warning of the scam!

A shorter explanation is Scam  #11, as shown at
http://phonehelp.2truth.com/facts.html

That site also shows how other 800notes visitors have reduced the number of telephone scams and telemarketing calls they receive. (That site also has a link to Amazon's phone blocker devices and apps, as well as a page showing various government sites that accept complaints or warn about scams.)

OMG Hilarious, can't stop laughing after trying to understand the msge he left!
Did not understand a word he said, didn't even realize when he said "AI--AREE-[***]" = IRS !!!

own money to IRS

Same thing happened to me.