Telco giant Optus has been told it will be held accountable after a serious triple-zero outage, as the role of private companies in delivering emergency calls is reconsidered.

Pressure continues to mount on Optus after last Thursday’s major outage that has been linked to up to four deaths, including that of a newborn baby.

It’s the second time in two years an Optus network issue has prevented Australians from accessing the emergency line, fuelling anger over its failure to implement the recommendations from a review into the first major outage.

Early investigations into Thursday’s incident appear to show established processes were not followed, with a botched firewall update blocking hundreds of triple-zero calls from Optus customers in South Australia, Western Australia and the Northern Territory.

On Monday, there were reports that calls in NSW had also been affected.

The deaths of a 68-year-old woman from the Adelaide suburb of Queenstown, a 74-year-old man from the Perth suburb of Willetton and a 49-year-old from the Perth suburb of Kensington have all been linked to the outage.

An eight-week-old boy from Gawler West, north of Adelaide, also died after his grandmother was unable to get through on a triple-zero call. But SA Police have since said the outage was “unlikely to have contributed” to the infant’s death because the grandmother immediately used another phone on a different network to call emergency.

Two customers contacted Optus call centres early last Thursday morning to alert it to the outage. The issue was eventually fixed after more than 13 hours.

A review has uncovered three more calls relating to the issue. Optus chief executive Stephen Rue said “red flags” were not raised because call volumes were normal.

His assurance there will be no repeat incident came despite a barrage of criticism of Optus for failing to implement recommendations from a review into a similar national outage that crippled the network.

About a third of the 18 review recommendations stemming from the 2023 outage, which resulted in fines totalling more than $12 million, are yet to be implemented.

Federal Communications Minister Anika Wells said Optus would face the consequences of its actions.

“This is the second significant and egregious failure on the part of Optus,” she said on Monday.

“They have perpetuated a failure upon the Australian people with what has happened here, and they can expect to suffer significant consequences.”

Communications watchdog chair Nerida O’Loughlin said Optus could be slapped with similar fines to after its previous outage.

The Australian Communications and Media Authority is investigating the latest incident and could also seek commitments from Optus to improve its processes.

Thursday’s outage, which Optus publicised only late on Friday, came 18 months after rival Telstra also failed to comply with emergency call rules during a triple-zero network disruption.

Asked about private companies’ responsibility for delivering emergency calls, Wells said she would need to review the issue.

“This isn’t entirely a matter for Optus,” she said.

“We are now considering what needs to be done holistically or as part of legislative relief for the Australian people, given their confidence has been shaken.”

Optus has also copped criticism for a lack of timely and accurate communication over the outage.

Wells said her first update was an email about an outage affecting 10 calls on Thursday afternoon. Her office received no further information until 24 hours later, when it was told the outage had affected 600 calls.

It wasn’t until the department got in contact that Wells found out about the deaths.

Speaking from New York, Prime Minister Anthony Albanese said Optus’s behaviour was “completely unacceptable”.

Federal Liberal MP Tim Wilson raised questions about Optus’s overseas call centres, including whether they had managed triple-zero calls or if they had received the initial complaints from customers.

Asked how Optus could be trusted into the future, Rue – who is facing calls to stand down – leaned on an independent investigation into the incident.

“We will make the facts public, and I can assure you, we will be implementing everything,” he said.

-AAP