These wall intercoms are located around the Galactica:
Let me tell you, these are pretty hard to find. Unless you happen to live near an old Navy port or some other place with navy surplus galore. This is a US Navy LS-541/SIC intercommunications station made by Audio Equipment Co. Inc. It's probably about 1960s vintage. Here is the one I have, it's the LS-542/SIC model with two rows of switches (for a total of 20 stations - I guess that means my personal battlestar is bigger than theirs).
I've already removed the speaker cage, but to make it more correct, I'd have to install a new speaker cover under the inside ring to match the one on the show. These are substantial pieces of equipment. Heavy and tube-driven. It looks like they probably removed the face plate, left the guts behind and mounted the front piece on the set walls. Here is a pic from the manual that shows the LS-541/SIC next to the LS-542/SIC:
