Emails and text messages released to 9News have revealed the scramble inside Optus after it discovered last week's triple-zero outage.
The first email was sent to the Federal Department of Communications on Thursday, September 18, at 2.45pm.
In it, an Associate Director of Optus Government Affairs writes they have "just been informed that Optus has received reports that some customers in SA and WA are experiencing impacts to triple zero calls."
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"Suspected cause has been indicated to stem from our Regency Park exchange (which services SA and WA), this matter is urgently being worked through."
Just seven minutes later, a second email is sent, in which the staff member states, "The work to rectify the issue is complete and services have returned to normal."
The Optus worker adds that "protocol reporting shows that 10 calls may have been impacted – each call is being worked through, and welfare checks will be made."
It would be another 24 hours before staff at the Department of Communications became aware of the accurate scale of the outage, which severed access to the triple-zero service to hundreds of customers.
Felicity Ross, Optus's Chief of Corporate Affairs, sent a text message to the chief of staff for Communications Minister Anika Wells.
"Please give me a call when you get this re a major issue. Thanks"
That text message was received shortly before media outlets were alerted to a press conference regarding an "Optus issue".
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Emails to the Department of Communications indicated the suspected cause of the outage was related to the "Regency Park exchange", which has since been confirmed by an Optus spokesperson.
"We can confirm that the outage was related to a firewall upgrade of the Regency Park exchange located in South Australia, which is why emergency calls were only impacted in certain states and territories serviced by this exchange."
"Optus advised the Minister's office of this issue and later provided a further update based on the information we had at the time."
Optus Chief Executive Stephen Rue has also blamed the issue on human error.
"That's not an investment issue, that's people not following process."
Yesterday, Optus was hit with a separate $100 million fine for selling products to hundreds of vulnerable customers, including some with a mental disability.
Minister Wells today signalled the company shouldn't "be surprised to hear" they can expect more significant fines.
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