This is the so called "area call panel" and it is indeed used to signal the cabin crew. The colours and their respective meaning is not regulated and depends on the aircraft and aircraft manufacturer.
A selection of colors, manufacturer and type according to airliners:
Boeing / McDonnell Douglas: Pink - Flight crew to FA call ORFA to FA call Blue - Call to FA from passenger in seat Amber - Call to FA from passenger in lavatory Red (717 only) - Lavatory smoke detector set off Green (DC-9 only) - Unused, included as a placeholder for an unknown function.
- Pink - Flight crew to FA call ORFA to FA call
- Blue - Call to FA from passenger in seat
- Amber - Call to FA from passenger in lavatory
- Red (717 only) - Lavatory smoke detector set off
- Green (DC-9 only) - Unused, included as a placeholder for an unknown function.
Airbus: Red - Flight crew to FA call OR (some aircraft only) FA to FA call Blue - Call to FA from passenger in seat Amber - Call to FA from passenger in lavatory Flashing Amber - Lavatory smoke detector set off Green (some aircraft only) - FA to FA call
- Red - Flight crew to FA call OR (some aircraft only) FA to FA call
- Blue - Call to FA from passenger in seat
- Amber - Call to FA from passenger in lavatory
- Flashing Amber - Lavatory smoke detector set off
- Green (some aircraft only) - FA to FA call
Further down you can read, that Bombardier Dash 8 uses solid green for a regular call and flashing amber for emergency call.
A definitive answer can only be found in the respective aircraft or crew manual.
