Don't answer or call back. I called back got a very thick accent male, asked me for my name right after answering i said you called me i'm not giving you any information, he put me on hold and came back on the line WITH MY NAME!!!! I asked for proof for owing anything, i asked for dates of correspondance to me,told him there was not way the us federal government would call and threaten this way, He put me on hold and low and behold we got disconnected.. ASSS's Isn't there somewhere to report this number to the IRS.
I just registered a complaint with TIGTA and will do the same on FTC.gov in a minute..:) if you go there, put "IRS Telephone Scam" in the notes. I wish these folks would get a real job instead of being parasites.