Found this answer online: „Many years ago big cities in the United States had a sort of telegraph system for reporting fires. Wires were run underground to red metal boxes on poles at strategic street intersections. If a passerby spotted a fire, they could pull a handle in the box, sending a coded signal to the fire stations. The firefighters would check the code to find the location and respond to that intersection. As the fire departments got bigger, specific stations were assigned to respond to these “boxes” so the whole department did not show up on the scene.”