Optus boss Kelly Bayer Rosmarin has revealed that more than 200 emergency calls failed during the telco’s nationwide outage that left millions without phone or internet services.

During the 12-hour network outage on November 8, Australian individuals and businesses were unable to make calls, access the internet or complete transactions.

Bayer Rosmarin told a Senate inquiry on Friday that Optus was unable to investigate why 228 calls did not go through for mobile customers as “we don’t manage the triple-0 system”.

Under Australian law, telcos are required to provide emergency call access at all times. Welfare checks had since revealed all 288 people involved in those calls were OK.

“We absolutely believe the triple-zero system should have worked and it’s critical for all Australians that the system can be relied upon,” Bayer Rosmarin said.

“[But] we don’t manage the triple-zero system, it’s a very complex system that involves all the carriers, it involves the device manufacturers.”

Asked by committee chair Sarah Hanson-Young if Optus knew why customers were unable to make the calls, Bayer Rosmarin said some inquiries had been made but Optus couldn’t fully investigate due to “complex relationships”.

“It’s too early to tell where the issue actually occurred,” she said.

“The triple-zero system is supposed to be able to pick up the traffic when we have an outage like this.”

Hanson-Young accused Optus of attempting to “share the blame” when it should take responsibility, apologise and accept a penalty.

“It’s not anybody else’s fault Optus customers couldn’t call triple-zero, surely it’s Optus’s fault,” she said.

Bayer Rosmarin also revealed the outage was so unusual there had been no emergency planning for an event of such scale.

“It’s not something we expected to happen,” she said.

During the outage, millions of individuals and businesses were unable to make calls, access the internet or complete transactions, and many did not find out the extent of the issue until hours later.

“You provide a service to over 10 million people and not just individuals – government agencies, emergency services, businesses – and all they got for hours, was a couple of lines that said, ‘sorry our service is out, we’re working on it’,” Hanson-Young said.

“For a communications company, the communication is pretty lousy.”

Bayer Rosmarin revealed that 8500 customers and small businesses had so far contacted the giant telco seeking compensation.

She said Optus was discussing about $430,000 in compensation, and $36,000 had already been applied or “paid out”. It was unclear if that was in cash or kind.

The company has also apologised and offered customers – including businesses that lost thousands in sales – 200 gigabytes of extra data, or free data on weekends as a “gesture of thanks for their ongoing support and patience”.

Bayer Rosmarin opened her address to the Senate inquiry on Friday by acknowledging the pain of her customers.

“While I believe wholeheartedly that we did everything we could to provide timely, accurate and credible information [but] I acknowledge that there is always more we could have done,” she said.

“Beyond restoring our network, our focus now is restoring trust.”

But the wrath of senators quickly became apparent.

“You provide a service to over 10 million people and not just individuals –  government agencies, emergency services, businesses – and all they got for hours, was a couple of lines that said, ‘sorry our service is out, we’re working on it’,” committee chair Sarah Hanson-Young said.

“That just is not good enough.

“For a communications company, the communication is pretty lousy, both in the time of the crisis and in the aftermath.”

The Greens pushed for and secured the inquiry the day after the outage and Hanson-Young vowed to examine Optus’ responsibility to look beyond its profits and protect the public.

The Australian Communications and Media Authority is also investigating Optus’ compliance with the rules on emergency calls.

Bayer Rosmarin has said the telco will co-operate with reviews launched by the government and the Senate.

The company initially blamed the outage on a routine software upgrade but its updated submission to the inquiry revealed it was due to default settings on its routers.

“Although the software upgrade resulted in the change in routing information, it was not the cause of the incident,” the submission states.

It took longer than expected to restore the system because some routers had to be physically rebooted in a “brute force resuscitation of the network”. That required sending Optus staff to sites across the country.

The outage began at 4.05am and was addressed in a crisis meeting at 7.45am. Bayer Rosmarin said she contacted Communications Minister Michelle Rowland after that.

“When I spoke to the Minister, I shared all the information that I knew from the crisis management team – and it wasn’t very much because at that point, we had no idea what had caused the issue, nor restoration time,” she said.

Throughout the initial period, Optus’s 24-hour staff tried to remedy the issue as the board worried over whether it was due to a cyber attack.

“There were some strange coincidences that made us quite worried about that,” Bayer Rosmarin said.

Representatives from the telco’s parent company Singtel were in Australia when Optus was targeted by a major cyber attack in 2022. They were also here when last week’s outage occurred.

– with AAP