Service Interphone System
The service interphone system provides intercommunication between the flight
deck, Flight Attendants, and ground personnel. Flight deck crewmembers
communicate using either a separate handset (if installed) or their related ACP
and any standard microphone.
The Flight Attendants communicate between flight attendant stations or with the
flight deck using any of the attendant handsets. Anyone who picks up a
handset/microphone is automatically connected to the system. External jacks
for use by maintenance or service personnel can be added to the system by
selecting the service interphone switch to ON. Communication between flight
deck and flight attendants is possible regardless of switch position.