By LAW the telephone companies MUST put all phone calls through. Unless YOU block the call. That's why phone companies and phone manufacturers supply the tools, but don't do it. YOU have to. They're working on changing those laws right now.
Think about it....where on your 1040 do you give the IRS your phone number? Nowhere! They don't want to deal with you over the phone because all they can/should deal with is facts! What did you claim, can you prove you paid it, is it a legitimate deduction. A phone call isn't proof. Just say "You aren't the IRS," and if the scammer can hear you over the noise in the "boiler room" he's working in, he'll hang up! Then call back a dozen times and jerk them around, just for fun!