Received hang up in voicemail.  Number blocked.

Was receiving phone calls from this number for couple of months and I never pick up the phone so then i got strange voice mail from the machine that is IRS calling

IRS Scam call.

That is a full blown scam.  Let me guess....the caller had an obvious foreign accent yet an all too American name such as "Bob Smith".  Call them back repeatedly either saying nothing or hanging up.  Eventually they will block your number but at least they get a taste of their own medicine.  Btw the irs NEVER contacts you initially by phone.  Their mode of communication begins with the US mail.