Optus is facing potential penalties exceeding $250 million after Australia's telecommunications regulator launched Federal Court action over last year's nationwide outage that left hundreds of Triple Zero calls unable to connect.

The Australian Communications and Media Authority (ACMA) on Thursday announced legal proceedings against the telco over the September 2025 outage, alleging it breached emergency call obligations on 1,005 occasions.

The outage crippled the Optus network for almost 14 hours, causing more than 450 Triple Zero calls to fail.

The incident has since been linked to two deaths.

ACMA alleges Optus failed to provide customers with access to the emergency call service and failed to ensure those calls reached the relevant emergency call termination point.

Each alleged breach carries a maximum penalty of $250,000, exposing the telco to fines of more than $250 million if the court finds against it.

The legal action marks the regulator's toughest response yet to repeated failures affecting Australia's emergency communications network.

‘Fundamental legal obligation’

ACMA chair Nerida O'Loughlin said ensuring Australians can reach Triple Zero was a core public safety responsibility.

"Australians rightly expect that when they call Triple Zero, their call will connect," O'Loughlin said.

"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."

The September outage was later examined in an independent review commissioned by Optus, which found a series of widespread failures contributed both to the network collapse and the lengthy restoration process.

Earlier this year, Optus chair Scott Perkins said employees responsible for the outage could face financial penalties and disciplinary action.

The latest court action follows a separate enforcement case over the telco's November 2023 outage, when Singtel Optus subsidiaries paid more than $12 million in infringement notices relating to failed Triple Zero calls.

"The recurrence of a major network outage affecting emergency calls so soon after the November 2023 outage is a significant concern and one of the reasons the ACMA has decided to take this matter to court," O'Loughlin said.

"ACMA will not hesitate to take strong enforcement action where alleged telco failures have jeopardised public access to the critical emergency service."

The regulator is seeking declarations that Optus breached the Telecommunications (Consumer Protection and Service Standards) Act, in addition to financial penalties.

Optus looks to future

An Optus spokesperson declined to comment on the legal action taken by ACMA and said the company remained focused on "building a stronger and better Optus".

"We continue to invest in network resilience, strengthen our systems and processes, build and foster a culture of transparency and accountability and improve the services our customers and communities rely on every day," the spokesperson said.

Communications Minister Anika Wells welcomed the court action, describing the alleged failures as "serious".

"Australians rightly expect to reach Triple Zero when they need it most, and telcos are legally obligated to ensure that connection occurs," Wells said.

The case comes just weeks after another major telecommunications outage by Telstra disrupted payments, train services and blocked some Triple Zero calls.

Telstra blamed the outage on a fault with a time synchronisation server.

It later emerged the failure may have stemmed from a 20-year-old server worth about $30,000 that had not been replaced, with the telco now facing potential fines of up to $30 million.