I know right - call back and have fun with them. They'll hang up on you if you tell them you are not giving your name because they called you and should have provided a number to reference. All of a sudden, click. Idiots!
They have some low life woman leave a message that the IRS is after you. Since when does the IRS have such ignorant morons working for them? No one from the IRS calls you and leaves a threatening message. Couldn't they have found a more authentic looking phone number? They are calling to scare people and scam money from them. I hope they rot in hell.