An Optus triple zero failure impacted around 600 customers in South Australia, Western Australia and the Northern Territory, with three of the failed calls involving a household where somebody died.

Optus chief executive Stephen Rue said the technical failure affected about 600 triple zero calls getting through in SA, NT and WA.

Rue said the failure had now been rectified and welfare checks had been conducted at all affected households.

From those welfare checks it was established that three of the calls came from households where people passed away.

”Our investigation is ongoing but at this stage I can confirm that approximately 600 customers were potentially impacted, of which a portion of calls did not go through,” he said.

He apologised to the families of those who passed away.

“I am so sorry for your loss.”

“What has happened is completely unacceptable. We have let you down. You have my assurance that we are conducting a thorough investigation.

”This should not have happened.”