I received a voice mail today (9/1/15) stating from this number as well with the exact message "this is a notice that the IRS is filing a law suit against you. I called the number I spoke to a male person with a thick accent (I believe from india descent). When I told them that I contacted the IRS main hotline, he claim that he did not call me. He then asked for my age (which I did not provide) and asked if I wanted to be his friend. Definitely a scam.
Just received telemated call from 360-200-6820, googled #, appears to be bologna. Go to https://www.treasury.gov/tigta/press/press_tigta-2015-01_home.htm to report.