[GreenKeys] What is this sign, RR or Teletype?

[Trent Condellone]

Hi!

I have had this for years, and since I am selling all my stuff and it is in 
the way out it goes. My problem is that I do not know what it is... I have 
been told that it is for the rail road offices that were here, and also 
that it was sign used by Bell System or Western Union or Teletype... any 
ideas as to what this is would be most helpful for me, not just so I can 
sell it - I just want to know once and for all!

Trent

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=130&item=744591342