@Mame,
I know Nurses have awefully long shifts.
The woman who committed suicide, answered the phone I believe, at 5.30am in the morning as there was no receptionist. I can only imagine, that she probably had already been working 10hrs by that time or there abouts. Can we really think clearly working that many hours, at that hour? I also believe that Nurses aren't scheduled to the same time day in, day out and so their body clock has to get out of wack.
Maybe that is the reason why she didn't pick it up, that it wasn't the Queen. Who knows.
I am sure that somewhere I did read that she had other issues and the Hospital was helping her with that, this probably was the final straw, she probably thought she would lose her job be sent back home, be homeless, be a shame to her family... Culture perhaps also may have played a part.
Still it is sad. And, still, I think the Producers should think of consequences of all actions before making a management decision on any pranks.