People can safely disregard this message. Robocall or not, these bogus operations are based overseas and some are probably changing their tactics. The fact is the IRS would not make contact by phone.

This scam is nothing new. The fact that the operation is based overseas makes it more difficult to go after these telemaggoters.

So I did check the other # that called me right after the 415 # , 1800 829-1040.  Apparently that is an IRS.    A Pittsburgh newspaper had written about this scam last November and referred to the 1800 829-1040 as a # to call.  However, perhaps this scammer organization has figured out how to make the call look like it is coming from the IRS (1800-829-1040) when it is really the 415 #.   So okay to call 1800-829-1040,  just don't pick up a call from this #.

I got this morning a message .. saying call back on this hot line before IRS takes an action against you
415-234-9577.
I left a message sincerely explain the reason for delay of taxes :-).
Then my CPA said it is not IRS call.  
I called back same number and one Indian Guy attended.  When I asked him IRS Badge number he was talking very bad language which I can understand..  I scolded him he kept phone down/

I will chase them

It isn't worth entertaining these operations. The last thing you want to do is confirm your number and increase the chances of  getting more calls. The clowns are overseas and that is one of the biggest issues with these telemaggoters.