Who called from 3478577921

Caller claimed to be from Microsoft and calling about "messages from your computer".  Sounds like a scam.

It is  scam.  Microsoft does NOT cold call you.

Caller from that number claimed to be from the IRS Investigation Department. Thickest Indian accent I ever heard!

I just got a call from that number saying to be from the IRS Investigation Department.

The IRS will not call you.  These a scams and the best thing to do is block the calls or at least do not answer them.