What do you do when you have Prince Harry's phone number? Well, you prank-call the royal just to hear his voice over the telephone.

That's exactly what Margot Robbie did after Cara Delevingne gave her Harry's phone number. Speaking to The Sun, the 27-year-old actress said that she called Harry after the model-turned-actress pushed her to make the prank call when they had time to spare while on the sets of the 2016 movie Suicide Squad.

"Cara knows Harry and while we were filming Suicide Squad she was like, 'Let's prank-call him'," she told the publication. "I said, 'We can't prank-call ­royalty', but anyway we did — and he was so cool with it."

What did Robbie say to Harry over the phone? Well, she did not reveal the details of their conversation but said "Prince Harry is so nice. England literally has the coolest royalty in the world". She added that Meghan Markle's fiancé can take a joke.

Embarrassed having made the prank call, Robbie then revealed that she crossed paths with Harry at a party thrown by model Suki Waterhouse in London in 2016. She said she initially did not recognise Harry as he was wearing comedy specs and was in between Princess Eugenie, Sienna Miller, Poppy Jamie, Cara and herself when taking pictures inside a photo booth at the bash.

"There were maybe five of us in this photo booth and I didn't realise until I was inside that one of the people was Prince Harry," she said. "He loved the booth though, I think he should get one for the wedding for sure."

Robbie also said she as a child thought it impossible for a girl from the Gold Coast, who started acting with a very thick Australian accent, to make it to Hollywood.

"They had to hire a dialogue coach to soften my accent because it was too Australian. Crocodile Dundee, that was me," she said. "My upbringing on a farm made Hollywood seem unattainable — it made it seem much further away."

Robbie has been nominated for Best Actress for portraying the role of skater Tonya Harding in I, Tonya at the 2018 Oscars.