23-00 Communications Graphics
23-01 Flight Deck Speaker System
23-02 Passenger Address System (PA)
23-03 Communications Systems (VHF)
23-04 Crewmember Interphone System
23-06 Selective Call System (SELCAL) (ATSCALL)
23-09 ACARS System
23-10 Cockpit Voice Recorder System (CVR)
23-12 Emergency Locator Transmitter (ELT)
23-14 Headsets/Headphones
23-16 Push-To-Talk (PTT) Switches
23-17 Flight Deck Hand Microphones
23-19 Alerting System (Audio/Visual)
23-20 Handsets
23-27 Data Link Communications
23-28 Flt ATTN LCD Touch Screen
23-30 Medical Consultant Communication