That doesn't show it's real. I'm not denying that the recording exists or that the recording was made available by Qantas.
I'm saying it doesn't sound like a recording of an actual PA made on an actual aircraft that was actually in revenue service. It certainly is not recorded by someone who "had a phone handy". There is no background noise, no whirring engines, no reaction from the passengers. To me it sounds like something that was recorded in a studio and had a filter put on it to make it sound vaguely like a PA.