A call box is a two way radio mounted in a fixed location, it can communicate with other two way radios at your facility. Intercoms and call boxes are essentially the same. The difference between them is simple. An intercom is designed for indoor use. A call box is more rugged and waterproof so it can be used either indoors or outdoors.
Are you aware of the many benefits that wireless callboxes provide? They can be used in a myriad of locations and applications. See how call boxes were used by these scientists in this Quick Video of Amazon Tall Tower Observation Project and think about how your company might benefit from using call boxes.