Call--and answer

Intercom panel and stereo speaker. Warning: intercom details and geekery below.

 

Some rooms (I believe here, the music room, and the bench room) had these large intercom speakers in pairs, for stereo sound; one of each pair was the master, having tone, function and call/answer controls. The smaller single intercom panels, which could still play music and call/answer, were in all four bedrooms, the upstairs hallway bathroom (really!), the sun room (despite the fact that you could hear anyone talking in the kitchen, where the main intercom master was, from there) and the dining room, with simple answer speakers at the front, side and back doors that also had doorbell buttons, making a total of twelve stations. For all I know, there was another in the guest house and/or garage. The intercom panel was not the type which could access stations individually, though even if it had been a master that can operate 16 extensions doesn't necessarily mean sixteen are installed. This was a decentralized system, where the individual panels have talk/monitor/listen controls but the master panel doesn't have switches for the stations, just a general inside, outside, both, off.

Done