This caller is saying he is someone rep. the IRS, pursuing a lawsuit for the IRS over a debt, and needs your lawyers number and other info. This is fake, the IRS, as you know will contact you directly through a letter pertaining to a debt. Not use a third party.
It's an IRS scam. Someone that is wanting you to pay a debt to the IRS, or face a lawsuit.
Had the same thing, and I know I don't owe them anything, I called the IRS to earn them about this caller after seeing about there was a debt just in case.