We had a pop-up page warning of a 'virus' being detected, purportedly from a 'Vocus Pty Ltd' (which does exist, it's a business connection supplier) and requests we call this number (1300 298 140) to avoid the consequences. That's a USA format for a number, not an AU one. This on a Mac via two router stages.

I'll see if I can find a reverse-lookup for the US,