BBC News reports that the Australian Communications and Media Authority has found in a preliminary report that 2Day FM, the radio station responsible for the hoax, acted illegally by airing the phone call without consent.
The prank call, which was made by radio hosts Michael Christian and Mel Greig, is currently being investigated by an Australian Federal court.
The hoax happened last year while the duchess was hospitalized for pregnancy morning sickness. Greig and Christian called Kate's hospital pretending to be Queen Elizabeth II, fooling nurse Jacintha Saldana into passing along the call to Kate's ward. Two days later, Saldana was found dead in her home after hanging herself.
Since the controversial hoax, both Greig and Christian apologized for the prank before their show was cancelled in the wake of Saldana's death.
"Just on our royal prank call...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," Christian wrote on Twitter at the time. "We're very sorry if we've caused any issues and we're glad to hear that Kate is doing well."