The chairman and CEO of embattled telco Optushave been grilled at a Senate inquiry into the catastrophic triple-zero failure that left three people dead.
Human error during a firewall upgrade in September led to an outage in multiple states and territories, which led to customers being unable to call the emergency line.
Speaking at a Senate inquiry today, Optus CEO Stephen Rue admitted the mistakes made by the telco during and immediately after the outage.
READ MORE: Boy, 11, killed in quad bike crash on Darwin mango farm
"There is no doubt that the timeline shows there were delays, there were mistakes made," he said.
"The tragic deaths of people during this outage stay with us as individuals and as a company as we investigate the incident.
"I fully accept there are aspects to the way events unfolded and how they were communicated over September 18 and 19 that we should have handled better."
Rue said correct steps and procedures were not followed after the company became aware of the outage and admitted that despite the offshore call centre believing the network hadn't failed, the issue should have been escalated.
"This was a unique situation whereby the call centre people believed the network was not failing, but they should have escalated those calls," Rue said.
"The initial mistake, a human error, occurred when the wrong process plan was selected for a routine firewall upgrade.
"The selected plan did not divert traffic before locking equipment inside the exchange that routes triple-zero calls.
"This error was not detected because control steps were not followed and alarms were not acted on at the time."
READ MORE: Former prince Andrew to lose final military title
Rue insisted this was "an explanation, not an excuse".
He also insisted the company had not been misleading in its delay in confirming how many calls were impacted in the outage.
"I wouldn't characterise it as misleading, it was information as we knew it at the time," he said.
"Sadly, it turned out to be different, we accept that."
READ MORE: Shock CCTV shows moment man is snatched off the street in Sydney
The fallout has been disastrous for Optus, with the triple-zero failure the latest in a long line of incidents and issues at the company over the last three years.
Rue, who came into the company in 2023 after previous CEO Kelly Rosmarin resigned in the wake of a nationwide outage, is also under increased pressure to keep his job.
Two Optus executives have already announced their departure, but Rue received an endorsement from Optus chairman John Arthur.
"There were I think 10 failures here, 10 failures. And if you're asking me whether I am alarmed at that, I can assure you I am," he said.
"However, this man was brought into this company to make sure we became a company that didn't have 10 failures like that.
"Now that's his job, and I'm expecting him to finish it."
READ MORE: The concerning factor believed to be behind surging house prices
Rue said it was not the right time for him to step away from the company.
"I firmly believe that another change of leader at this time is not what Optus needs, or what our customers need," he said.
Optus has been criticised for having critical infrastructure and call centres located offshore, and Rue said the company had made changes as a result of the triple-zero failure.
"We will take back calls that relate to triple-zero calls and relate to vulnerable customers… and ensure that they are dealt with onshore in Australia. And we're in the process of doing exactly that," he said.
"Our contact centre procedures have been overhauled, including a mandatory escalation process for any customer reports of triple-zero issues."
DOWNLOAD THE 9NEWS APP: Stay across all the latest in breaking news, sport, politics and the weather via our news app and get notifications sent straight to your smartphone. Available on the Apple App Store and Google Play.
