The 14-hour outage during a network upgrade in September affected South Australia, Western Australia, the Northern Territory and parts of far western NSW.
Of the 605 emergency calls during that time, 455 failed to connect.
An independent investigation released by Optus on Thursday found the company and its contractor Nokia had made at least 10 mistakes during the upgrade.
It took Optus and Nokia 13 hours to understand the problem, with an Optus call center failing to escalate initial concerns from five people who said their triple-zero calls weren’t working.
Optus and Nokia also “astonishingly” attributed early warnings about the problem at a network operations center to the fact that upgrades were taking place, according to the report from veteran director Kerry Schott.
Once Optus was made aware of the issue, it was resolved within minutes.
“The real tragedy here was the duration of the triple-zero call outage and the inability of Optus and its contractors to immediately respond to the warning signals they received,” Schott said.
The cause of the outage was a failure to route voice calls, including emergency calls, before a gateway at a switching station in South Australia was closed.
The first of the 10 errors involved sending incorrect instructions to Nokia about the upgrade process, the report said.
The errors could only be explained by a lack of care and lack of compliance with procedure, Schott said.
Optus has pledged to quickly implement all 21 recommendations from the report, including better processes around upgrades and addressing the siled nature of work at the company.
The telco’s chairman John Arthur said the failures were unacceptable and the board was taking further action against individuals, including financial sanctions and possible dismissal.
“We are deeply sorry for the September 18 outage that affected triple-zero services and the impact on Australians trying to reach emergency services,” he said.
Schott said it was puzzling that only 66 callers could “camp” – a process in which emergency calls are routed through another network.
Some devices took 40-60 seconds to be redirected to another network.
“In an emergency situation, it’s unlikely that people will hang around that long, especially if the only answer they get is silence on the line,” Schott said.
“This delay is something that customers across all telecom companies need to be informed about.”
Standards and requirements for devices and providers to ensure emergency calls are successful may not have kept pace with technological changes, she said.
Political reaction
The Greens have called for a government review of the camp-on provisions and a review of Optus’ license and licensing conditions.
The federal government helped establish the National Telecom Resilience Center, which tests emergency call scenarios, including “camp-on.”
The outage was unacceptable and the country’s independent communications regulator continued its investigation, a spokesperson for Communications Minister Anika Wells said.
“Access to triple zero is one of the most critical requirements for mobile operators and ongoing work is underway to improve system resilience.”
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