Optus did not escalate at least five calls that were made to its customer service centre, including two from NSW, that informed the telecommunications company that a technical error was preventing customers from calling triple zero.
CEO Stephen Rue this afternoon confirmed that Optus had found a further three calls, additional to the two announced yesterday, 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.
READ MORE: Optus outage 'unlikely' to have contributed to eight-month-old baby's death
"As we had not detected the triple zero failures in our network at the time of these calls, there were no red flags for the contact centre to alert them to any live issues," Rue told media today at Optus' headquarters in Sydney.
"This is not clearly good enough and we are implementing a new compulsory escalation process following any customer reports of triple zero failures through our customer call centre.
"Because there was no indication of a general network issue. What the operators did was try and troubleshoot."
The inability to call triple zero affected South Australia, Western Australia and the Northern Territory between 12.30am and 1.30pm on Thursday.
A total of three deaths have thus 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.
Today Rue said two of the calls to Optus customer service complaining of the outage came from New South Wales – although this is likely because they were situated near the South Australian border and their calls likely connected to South Australian towers.
He said welfare checks had been conducted and that no serious injury or death had been reported as a result of the two calls in the state
Rue confirmed he had not yet listened to the calls.
"I have been doing a multiplicity of things, one of my senior members of my team has done that," he said when asked why he had not listened to the calls.
Rue said it was unlikely there was a surge of calls in this time or outages in any other part of the country.
"That is what our call logs show, and the team has looked at it on multiple occasions," he said.
"The call volumes in this case looked normal."
Rue also said the location of Optus' call centres, including some that are based offshore, had no bearing on the incident and was not a major focus of investigation for the company.
"The location is not really a topic for today," he said.
"What the topic is around our processes and ensuring that the processes are in place."
'Abhorrent behaviour': Politicians weigh in
Nationals leader David Littleproud said the telco had failed their responsbility to provide a "universal right" to Australians.
"It's abhorrent behaviour, they have a responsibility," he told Weekend Today.
"This is a universal service and a universal right for Australians to be able to use in their hour of need, and the fact that Optus has just, in some blasé way, ignored the risks that are there for Australians to be able to ring triple zero is just beyond belief.
"They do need to to face penalties for this, the fact that the government wasn't even advised until some many hours and days after is frightening."
South Australia Premier Peter Malinaskus said he expected more incidents to come to light.
"We're very cautious of accepting everything that Optus says up until this point," he said.
"There is still more work to be done in terms of our analysis of their conduct."
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