check https://www.consumer.ftc.gov/blog/another-tax-scam-irs-imposters - a gov site that says IRS does not call you, they send official notices by mail. This is a scam!
I had a message from this number on my answering machine. It said that it was the IRS and that I must call them before they "took legal action against me." Obviously I knew that if the IRS had a problem with me, they would not call me, but would contact me by mail. But for curiosity sake I did call the number back and a man with a foreign accent said "IRS." I let out a giggle because obviously he did not take into consideration that the IRS would likely have a computerized answering system. After I giggled he said "Oh, you think this is funny?" He then hung up. His stupidity would be funny if it weren't for all of the honest, hardworking people that are going to be scammed by this scum of the earth.
As stated above, don't bother calling the number because it is a scam. The IRS will never contact you via phone, let alone a computer generated phone call, for the purposes of collecting overdue taxes. The only reason to call them back is to have a little bit of fun at their expense. Otherwise, put this number on your block list.