A further seven Optus customers were unable to contact emergency services during the catastrophic triple-zero outage, the telco has confirmed.
Optus said it has reviewed call logs from last week's network outage and found there was a brief period between 12.17am and 12.30am when the planned upgrade was being "readied" which blocked triple-zero calls for customers.
The telco said it has contacted three of the households and found no further assistance was required.
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Two have been referred to WA Police and two to SA Police as Optus was unable to make contact with the residents.
Police said four of the seven calls were in WA and one of the incidents has since been resolved.
An investigation is now under way over the second call.
It was earlier believed that 624 triple-zero calls had been affected during the outage, which occurred between 12.30am and 1.30pm on Thursday in South Australia, Western Australia, and the Northern Territory.
Optus chief executive Stephen Rue yesterday confirmed the telco had found a further three cases, additional to the two announced on Friday, where customers had complained that they could not call triple zero.
Rue said the calls were not adequately escalated within Optus' system, meaning the telco was unaware of a major systemic failure until after 13 hours.
A total of three deaths have have so far linked to the outage.
A fourth, the death of an eight-week-old baby boy in Adelaide's north, was originally linked but South Australian police have said they believe the outage is unlikely to have contributed to the infant's death.
Optus to face 'consequences', minister promises
Optus can expect "consequences" after another outage left people unable to contact triple zero in an "enormous failure", Communications Minister Anika Wells said.
Multiple people died during the network outage, during which they were unable to reach emergency services.
Following Optus chief executive Stephen Rue's admission yesterday that the telco had missed several warnings that calls to triple zero were not going through, Wells this morning confirmed Optus had been told about the issue but not acted on it.
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"Optus will be held to account," she said.
"Optus and all telecommunications providers have obligations under Australian law to make sure emergency services calls go through."
Wells and Australian Communications and Media Authority head Nerida O'Loughlin did not specify what consequences Optus would face, but O'Loughlin noted that the telco had been penalised $12 million after breaching similar laws in 2023.
O'Loughlin said 624 triple zero calls had been affected during the outage.
She said initial emails from Optus about the scale of the outage had been "perfunctory" and "inaccurate".
Under existing regulations, telecommunications companies are required to tell stakeholders, including the government and ACMA, as soon as an outage is detected.
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"In this case we weren't notified at all until the outage was resolved," O'Loughlin said.
ACMA is undertaking a thorough investigation of the incident, though Wells and O'Loughlin did not say when they expected that to be resolved.
"Once we have the facts about what has happened and once I take the recommendations that come from the recommendation from ACMA, I will then consider what is an appropriate response for the telecommunications as a whole," Wells said.
The minister also indicated that the outage could prompt a broader examination of the industry, noting that Optus was not the only provider to have overseen triple zero outages.
"This is not entirely a matter for Optus," Wells said.
"We are considering what needs to be done holistically or as part of legislative relief for the Australian people, given their confidence has no doubt been shaken by what has happened here."
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