Received the same call on my landline...twice in one day! Per other comments, I'm not calling back to this scam. It's been on the TV news multiple times here in the DC area. As a former Fed, I assure you this is NOT how the IRS goes about it's business!
This number called twice stating that the IrS was filing a lawsuit against me. I called back to see what information I could get from them. I then contacted the IRS directly and they said to report SCAM at TIGTA.com and lick the red box.
Robo-call scammer left 2 voicemails today informing me about an IRS lawsuit. Instructed me to call the number to get more information. I reported the incident at https://www.treasury.gov/tigta/contact_report_scam.shtml