“RCA 4-line Expandable Speakerphone System install & usage questions. See details. Help! Say i purchase one 4-line expandable speakerphone unit with digital answer system & i hook up two incomming phone lines to it, like the manual indicates. Then purchase two more expandable speakerphone units. My question is, do i then need two more phone lines to each additional phone unit? If that is correct then i need to split my two incomming phone lines, each one three ways. Right? I will assume that the one machine with the answering machine will be the one that will pick up in the event no one is in the office? The manual does not indicate if i can or cannot record a greeting, & how long of a greeting i can record. Any help would be appreciated. Thank you.”