Optus is facing Federal Court action and a theoretical maximum penalty of $251.25 million over its September 2025 network outage, which left hundreds of people unable to reliably reach Triple Zero.
The Australian Communications and Media Authority alleges Optus Mobile breached two emergency-call obligations on 1,005 occasions. The almost 14-hour outage affected several states and territories and was linked to two deaths.
Optus has not been found liable, and no penalty has been imposed. The Federal Court will determine whether the alleged contraventions occurred and what penalty, if any, should apply.
Why ACMA is taking Optus to court
ACMA alleges Optus failed to give customers making emergency calls access to the emergency call service and failed to carry those calls to the required termination point, where an operator could answer them.
The regulator is seeking declarations that Optus contravened the Telecommunications (Consumer Protection and Service Standards) Act 1999 through failures to comply with sections 15 and 19 of the Emergency Call Service Determination.
ACMA also wants Optus ordered to pay penalties to the Commonwealth.
Could Optus be fined $251.25 million?
The maximum available penalty is $250,000 per contravention. Multiplying that by the 1,005 alleged breaches produces a theoretical ceiling of $251.25 million.
That is not a confirmed fine. The court may consider how the contraventions should be counted, their seriousness and other legal factors before setting any penalty.
The case seeks regulatory penalties rather than direct customer compensation. A court ruling against Optus would not automatically create payments for affected customers.
Where the Triple Zero outage occurred
The disruption began shortly after midnight on September 18, 2025, during work at the Regency Park exchange in South Australia. Emergency-call services were not restored until early that afternoon.
Customers were affected in South Australia, Western Australia, the Northern Territory and parts of far-western New South Wales. Ordinary mobile calls continued for many users, making the emergency-call problem difficult to detect.
How many emergency calls failed?
An independent review commissioned by Optus found that 605 callers sought emergency assistance during the outage.
Only 150 connected successfully. Sixty-six reached emergency services after switching to another carrier through the “camp-on” process, while 84 used another working route within the Optus network. The remaining 455 callers, or about 75 per cent, did not connect.
Some people may have tried more than once, meaning the number of call attempts differed from the number of individual callers. This helps explain why ACMA alleges 1,005 contraventions despite the review identifying 605 callers.
Optus was initially told of four deaths during the outage. Police later determined that two were unrelated, leaving two fatalities linked to the emergency-call disruption.
What caused the Optus outage?
The failure occurred during a routine firewall upgrade involving Optus and contractor Nokia. A gateway was locked without first redirecting traffic.
Normal calls quickly found alternative routes, but most emergency calls remained blocked. The review identified at least 10 mistakes involving planning, approvals, implementation and monitoring.
These included incorrect change instructions, Nokia’s use of an outdated procedure, three peer reviews missing the absent traffic-diversion step and the work being wrongly classified as urgent and having “no impact.” Important engineering and risk reviews were consequently bypassed.
Warnings were not escalated
Network alerts appeared at approximately 12:20am and 12:47am, but neither resulted in corrective action. Later checks showed increasing call failures, yet the problem was not recognised.
Five customers also told the Optus call centre that their Triple Zero calls were failing. Their reports were treated as isolated handset or local-network problems and were not escalated.
Optus only recognised the wider failure about 13 hours later after SA Ambulance contacted the company at approximately 1:15pm. South Australia Police raised the issue again shortly afterwards.
The review also identified poor internal information sharing, delayed crisis escalation and difficulties finding affected callers because failed calls had not entered the core network. Welfare checks began after their details were reconstructed.
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Why the 2023 outage matters
ACMA said the recurrence of emergency-call failures so soon after Optus’s November 2023 outage was a major reason for going to court.
The earlier investigation found preventable network-management failures and inadequate welfare follow-ups involving more than 360 customers. Singtel Optus subsidiaries subsequently paid more than $12 million in penalties.
More background on the company’s response is available in the report on the Optus Triple Zero inquiry and 21 reforms.
The proceedings come amid wider scrutiny of network resilience after a separate Telstra outage disrupted trains and payment services across Australia.
What happens next?
Government reforms introduced after the 2023 outage established a Triple Zero Custodian and strengthened outage communication, network testing and complaints-handling requirements.
Communications Minister Anika Wells welcomed the latest court action and described the alleged failures as serious. ACMA Chair Nerida O’Loughlin said access to emergency calls was a fundamental legal obligation.
Optus declined to comment directly on the proceedings but said it was strengthening network resilience, systems, transparency and accountability. The company can respond to ACMA’s allegations before the Federal Court determines liability and any penalty.
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