Stromberg-Carlson Speakerphone... any info?

[Nilsog]

Hey guys,

I posted a while back about getting this at a yard sale along with a butt set. I was messing around with it today and actually got it to work. I initially thought it was for a 2-way radio set but it seems to be a speakerphone of sorts. I made a video showing its operation if anyone is interested in helping me figure out what all the doodads are.

Clicky!

Any help would be appreciated... I'm kind of intrigued.