I dont want to get charged for calling, due to it having a distant area code in the phone number.
Hey, it's the 21st Century! Why don't you have a calling plan with unlimited, free, long-distance calling like just about everyone else does? Not to worry, though. The number (303) 440-0746 visible in your photo has been disconnected.
The company, Data Display Corporation, Boulder, Colorado, does not appear in any Google search. They probably went out of business sometime in the 20th Century. Competition in custom large-format LED display signs was pretty intense, circa 1970 and onward. Your best bet is gonna be to open it up and reverse engineer it to discover how it works. Maybe you can learn how to put an arbitrary message up on the LED display. Worse comes to worst, maybe you can salvage individual LEDs from the display. After all, it is just road-kill, riiight? OTOH, LEDs are dirt cheap, so maybe not worth the effort to salvage them.