The Tuesday morning prank call came from Australian DJ's Mel Greig and Michael Christian. They impersonated the royals, complete with exaggerated accents. They even enlisted two co-workers to bark like the queen's pet corgis.
The Sydney radio station, 2DayFM, could not be immediately reached for comment.
The Twitter accounts of both radio personalities have been deactivated, but it is unknown when the accounts were shut down. The DJ's are being heavily criticized on Twitter, with many people calling for them to resign or be fired.
"I'm just after my granddaughter, Kate. I want to see how her little tummy bug is going," the radio host said in the prank call, suppressing laughter.
"She's sleeping at the moment, and she has had an uneventful night and sleep is good for her," the nurse said. "She's been getting some fluids to rehydrate her because she was quite dehydrated when she came in, but she's stable at the moment."
The fake royals went on to ask when would be a good time to visit and were told that "anytime after 9 o'clock would be suitable."
"She's quite stable at the moment. She hasn't had any retching ... since I've been on duty. And she has been sleeping on and off. I think it's difficult sleeping in a strange bed as well," the nurse said.
The hospital apologized for the mistake.
"The call was transferred through to a ward, and a short conversation was held with one of the nursing staff," the hospital said in a statement. "King Edward VII's Hospital deeply regrets this incident."
"This was a foolish prank call that we all deplore," John Lofthouse, the hospital's chief executive, said in the statement. "We take patient confidentiality extremely seriously, and we are now reviewing our telephone protocols."
The radio station also apologized for the prank call.
"2Day FM sincerely apologizes for any inconvenience caused by the inquiry to Kate's hospital. The radio segment was done with lighthearted intentions," the station said in a statement.
"We were very surprised that our call was put through. We thought we'd be hung up on as soon as they heard our terrible accents," the radio hosts said in the statement. "We're very sorry if we've caused any issues, and we're glad to hear that Kate is doing well. We wish Kate and her family all the best."
ABC News' Bruno Roeber contributed to this report.