The wall speakers/ intercoms are unit: US Navy Intercom Station LS-386.
The unit I have is missing the metal tag seen on the lower left next to the wall attachment bolt (and below the handset connector).
Walk around the NASM (The Mall) as I did summer of 08 and into the Enterprise Aircraft Carrier exhibit. I counted about 5 or 7 of these on the walls. The exhibit hasn't changed since 1976 when it opened (IIRC), so they just weren't used on submarines- probably all over the US Navy.
I bought mine in early 2007 from an eBay seller who was advertising something that was close, but no cigar. He eventually found me one of these 32 1/2 lbs. beasts. (YES- my Mail Scale says thirtytwo and one half pounds:eek).
The unit protrudes 8 inches from the wall.
They unbolted it into two parts, and only used the front 2 inches (resin castings as the auction stated).
Lastly, the seller told me this: "Working units are still in demand by 2 world countries and I get more money for them than I am asking of you; but the forms required to sell outside US to a Foreign Country are mind boggling..."
Good luck everyone on their search!
MG