Who called from 3608511726

I received 3 calls within a matter of a couple of hours from this number on my land line saying it was the IRS about to bring a lawsuit against me.  When I called back the number just to see what would happen it answered as "IRS" with what sounded like an Indian voice.  I just muted my phone and listened to what was going on in the background.  Sounded like lots of people making calls - probably similar scam calls as the ones I got.

caller states they are the IRS. . .

says they are Internal Revenue ServiceS  -however the gov IRS has no 'S' at the end of Service
probably a scam

3 different days the robotic voice said this is "final notice" that the IRS is filing lawsuit against me and I should call this number for more information. (The real IRS knows where I live & will send certified mail if they have anything to tell me, so I know this must be a scam.)

Fake IRS call. First call at  709am and have called 6 times today.  I blocked them right away but from my phone log, they keep on calling.