How about having an option on the Inflight Entertainment Screen to order a drink or snack and the light above is Blue but in an Emergency you either press the Red Button and the light flashes Red with three tones pause three tones etc. being heard in the galley. A double tone for non emergencies.

Or on other planes who do not have the IFE system you press a Red Button for an Emergency and a Green Button for other non urgent needs.

OnStar in the car has different buttons one for SOS one for the Concierge.

Just my two cents.