left message that IRS was threatening law suit and asked for call back to get details!

Call blocked - caller id says wireless caller and not irs

Called me 3 times yesterday. Twice it came up as private number. Then came up once as this wireless caller. Claimed to be IRS and that there was an on going case against me. I did not answer. They did not say my name on the phone. It is a Robo call. This is not the IRS. They would mail a letter if they want to contact you.