SSPRAM

What is SSPRAM?

No clue on that one. Where did you read it?

How does SSPRAM (solid state pre recorded announcements and music) work? is it equipped with a subsystem to detect phase of flight to automatically make appropriate announcement?

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.