that nobody could have reasonably foreseen the consequences of what has been described by the hospital as an "appalling" hoax.
He said he was satisfied that the appropriate checks were conducted before the pre-recorded segment was broadcast.
"It is absolutely true to say that we actually did attempt to contact those people on multiple occasions," Holleran told Fairfax radio.
"We rang them up to discuss what we had recorded."
"We attempted to contact them on no less than five occasions," he added. "We wanted to speak to them about it."
Holleran did not say whether the broadcaster was given any response.
The prank call was vetted by lawyers before being aired to listeners in Sydney last week.
The hoax call, with 2Day FM presenters Mel Greig and Michael Christian posing as Queen Elizabeth II and Prince Charles, was taken by mother-of-two Jacintha Saldanha, 46, at London's King Edward VII Hospital.
With no receptionist on duty she put them through to a colleague who divulged details of Prince William's wife Kate's recovery from severe morning sickness.
Saldanha was later found dead, believed to have taken her own life, sparking a massive backlash against the radio station and the two presenters, who have gone into hiding and are undergoing counselling.
"No one could have reasonably foreseen what has happened," said Holleran, adding however that the station was reviewing its actions.
"We think that's an appropriate thing to be doing and we'll do it," he said.
His comments came after Southern Cross Austereo held an emergency board meeting Sunday to discuss the growing furore, vowing to cooperate with any investigations.
"As we have said in our own statements on the matter, the outcome was unforeseeable and very regrettable," company chairman Max Moore-Wilton said in a letter to the hospital's chairman Lord Simon Glenarthur.
"I can assure you we are taking immediate action and reviewing the broadcast and processes involved."
According to the Sydney Morning Herald newspaper, all Austereo staff were called to a meeting on Monday morning with employees ordered not to speak publicly.