Everyone here was assuming that each room had a simple push button with wires back to the display panel. We now find out that each room has a "communication" device to inform the control panel what to display. That completely changes the ball game.
I'm still a little confused. Say five people in rooms press their button and (I assume) five LEDs light, you press the cancel button, what happens? Or, is there a cancel button in each room?
There are so many unanswered questions that it's impossible to come up with a design.
It may be possible to make a design that simply looks at the LEDs and displays a number but it would need a processor to remember the order that LEDs were lit so it can display the next priority number.
Mike.
Edit, Another problem is the LED display is probably a multiplexed display so the LEDs aren't constantly lit.