Phony IRS scammers.  Ignore 'em.  They are gangs of Indian or Pakistani extortionists.

See:  http://www.irs.gov/uac/Don%E2%80%99t-be-Scammed-by-Fake-IRS-Communications

I have been getting these calls for the past few days now and someone by the name of Mike John calls and says that he is from the income tax litigation department and that they found some discrepancy in my taxes and that I need to call him as soon as possible at 415-051-5012. I tried to find out who is this person calling me for the last several days with these stupid messages and when I call that # it says that the # has been disconnected.