Nurse calls can be hard wired or wireless. There are benefits to each method. Regardless, they are a standard form of intercom electronics. One critical difference with a Nurse Call is the actual device, which is usually a hand held control wired around the side of the bed so the patient has easy access to it. In most states, law requires both the location of placement and response time.
On the receiving end, the options range from simple light or audible alerts to a visual display complete with camera transmission.
See the link for INTERCOMS.