Live bed board for a hospital's admissions team

Your hospital has 600 beds on 20 wards. When a patient needs a bed, the bed manager phones the wards to find one that is empty and clean. The hospital wants a live bed board instead, shown on 40 wall screens and on staff phones.

Ward nurses mark a bed empty when its patient goes home. Cleaners mark it clean when they finish. The admissions team then gives a clean bed to a waiting patient. About 150 patients are admitted a day, and beds change state about 1,200 times a day.

Every change should show on every screen and phone within 5 seconds. A bed must never be given to 2 patients, even when 2 admissions staff pick it at the same moment. Wall screens sometimes lose the network for a few minutes.

What does the board store for each bed, and what happens from a tap on a phone to the change showing on every screen?