A voice recording, made by a person who doesn't identify itself, and doesn't know my name, called to say the IRS was filing a lawsuit against me and I should urgently call a 1-600 number. The IRS does not operate this way!
As others have mentioned I believe 408-256-0700 may have something to do with Project FI or Google voice. I'm a project fi user and on my caller id I received a call from 408-256-0700 at 6:30am but the email from Google said I had a missed call from (646) 650-3964.
I just switched to Google Fi and got a call from this number about "an important legal matter." They were looking for someone else. I blocked the number.