I answered the main phone AT WORK from this number just now, and it was just like the others described above - recorded message instructing me to call a caseworker regarding a pending lawsuit from the IRS. Obviously, it is a scam.
Automated voice recording stating that the IRS is filling a lawsuit against me and I needed to call back and talk with my case worker. Called back, but there was no answer. Obviously a Scammer, as the IRS would never operate this way.