Description (AMM 23-31-00)

A- The remote electronics unit contains the relays for speaker muting of the  appropriate speakers relative to the fwd or aft attendant microphones used to key the PA system.            

B- The Remote Electronics Unit is also used in the Flight Interphone System, and the Cabin Interphone System. Therefore, the Removal/Installation procedure is found in the Flight Interphone System manual (AMM 23-51-11/401).