I work on freighters. Boxes don't care.
As far as passenger systems, I'm sure there are several inputs into the entertainment/announcement system......
Flight information provided by the FMC's.
Altitude and speed from the Air Data computers.
Heading from the IRS's.
Most cabin announcements are pre-recorded and controlled by the cabin crew, but that doesn't mean they can't make their own at any time.
All can be overridden by an announcement from the cockpit.