"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 earlier.
The Sydney radio station - famous for its pranks and outrageousness - has suspended all advertising in the face an advertising boycott.
It was warned by Australia's broadcast regulator last spring about its violations of the "decency provision" of the country's broadcast code. Authorities are now looking to see if the radio hosts violated the criminal code, with some calling for charges of involuntary manslaughter.
The prank had been cleared by the Australian radio station's lawyers. CEO Holleran said the DJs followed the company's procedures before broadcasting the call.
"I think the more important question here is that we're very confident that we haven't done anything illegal. Our main concern at this point in time is what has happened is incredibly tragic and we're deeply saddened and we're incredibly affected by that."
The Associated Press contributed to this report.