Standard Electric magneto telephone

[dsk]

I have this magneto phone the make is Standard Electric, it is rare here, and the markings are strange.
I will be happy for everything you may teach me about this one. 
Thank you!

[RB]

Don't know much about it, but it sure looks clean! 
Looks like everybody else's LB wall phone. same construction.
Seems like an Anti sidetone???
Very nice, anyway!!!