They have various numbers.
They call from this number - 1-844-519-7722
Then they call back from a textnow number as well - 1-424-317-2526.
They start with gotoassist. Then install Teamviewer. And blacken your screen.
Also been tracked on RoboKiller https://lookup.robokiller.com/search?q=1-844-519-7722