The outage, which lasted for an hour and 16 minutes starting at 1.30pm on Friday, affected customers in Victoria, Tasmania, South Australia and the Northern Territory.
Optus provided authorities with details of 39 calls that failed to connect to triple zero during that time, according to Triple Zero Victoria chief operations officer Paul Santamaria.
Victoria Police said they completed around 40 welfare checks as a result of the outage, and that there were no adverse outcomes or issues of note.
The Tasmanian Department of Police, Fire and Emergency Management said it had been informed of three calls that were affected by the outage.
''Police subsequently contacted the callers, and it was determined they did not require immediate police or emergency services,'' a spokesperson for the department said.
Optus said in a statement that it identified the issue within minutes and immediately mobilised technical teams to restore services.
''We sincerely apologise to customers for the disruption," the telco said.
Senior federal minister Chris Bowen said investigations had begun into the outage, adding it was a "big relief" that everyone who was impacted appeared to be safe and well.
"It's deeply concerning that this has happened again, on a smaller scale than previously but still any breach here, any failure of service, is concerning," Mr Bowen told reporters on Saturday.
"It's an obligation on our telecommunications companies to keep all their technology for triple zero calls in the best possible working order."
The latest systems failure comes after the Australian Communications and Media Authority took Optus to court in July over the September 2025 outage that lasted almost 14 hours and impacted 600 calls.
The telecommunications watchdog alleged that Optus breached two legal obligations more than 1000 times during the outage, which was linked to two deaths.
"Australians rightly expect that when they call triple zero, their call will connect," the authority's chair Nerida O'Loughlin said in July.
"The circumstances of this outage meant that did not reliably occur, leaving people unable to connect to potentially life-saving services.
"Giving access to the emergency call service is not optional, it is a fundamental legal obligation and the most important public safety responsibility telecommunications providers have."
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