SYDNEY - Australia’s second-largest telco, Optus, had no crisis plan when a network-wide outage left nearly half the country without phone or Internet connections for 12 hours, an executive told Parliament on Friday, acknowledging the company’s defences had failed.

Optus chief executive Kelly Bayer Rosmarin said she was “deeply sorry” for the outage that cut mobile and Internet services to more than 10 million people.

“It is indisputable that, on that day, our performance was not acceptable. We let you down and for that I am deeply sorry,” she added.

The Singtel-owned company had recently war-gamed scenarios in which the routers that direct voice and Internet data failed in entire states, but it never expected a nationwide shutdown because it had alternate connections built into its network.

“We didn’t have a plan in place for that specific scale of outage,” Optus managing director of networks Lambo Kanagaratnam told a Senate hearing on the Nov 8 failure that left much of the country unable to make payments, receive healthcare or contact emergency services for most of a day.

“It was unexpected. We have high levels of redundancy and it’s not something that we expect to happen,” he added, using the telecommunications term for alternate routes to send data when an initial pathway fails.

The comments underscore concerns about the resilience of Australia’s telecommunications networks, which have been in the spotlight since a massive data breach at Optus in 2022 exposed the personal data of 10 million Australians. Now the company faces a fresh reputational crisis after the service blackout, which it has said was triggered by a standard software upgrade at Singtel.

The Australian government has already imposed tougher cyber security reporting standards on telcos, and has said it plans to introduce mandatory reporting of ransomware attacks in all sectors as part of an overhaul of the country’s cyber security laws to be announced in November.

Mr Kanagaratnam told the hearing Optus never expected a total shutdown because it had filters designed to stop all 90 of the company’s routers from being overloaded with data. But the filters failed, cutting the company’s ability to send data on alternate routes.

“The outage was a result of our defence not working as it should have,” he said. “Our network should have been able to deal with the change.”

The length of the outage – from about 4am to 4pm local time – was because Optus had to physically reboot all 90 routers plus another 50 core network devices, he added.

Ms Bayer Rosmarin described the hard reset of its system as “a brute force resuscitation of the network”.

When asked why the company took six hours to dispel public concerns it was under a cyber attack, she told the hearing “there were some strange coincidences that made us quite worried about that” because the Singtel board was in the country that day.

She said 228 calls to Australian emergency hotline 000 failed to connect because of the outage, but the telco had followed up all incidents and “thankfully everybody is OK”.

Asked whether Optus was overly reliant on third-party contractors, Ms Bayer Rosmarin said “it is something I do think we should look at, in terms of the right level of outsourcing and insourcing”.

However, she deflected questions about a media report she was considering stepping down over the failure.

The Australian Financial Review said she could leave as early as next week, citing sources close to the chief executive who spoke on condition of anonymity.

“My focus is on the team, the customers, the community. My focus is not on myself,” Ms Bayer Rosmarin told the Senate committee.

When pressed by the panel to deny or confirm the report, the chief executive said she had not read any reports in the morning because she had been preparing for the hearing.

Singtel has said that although Optus experienced an outage after its software upgrade, the upgrade itself was not the cause. REUTERS, AFP