The Australian Communications and Media Authority has opened an investigation into whether Telstra breached its emergency call obligations during the network failure that began at about 4.30am on Wednesday and left some callers unable to reach Triple Zero for the better part of two days.

Telstra carried out 639 welfare checks on people whose calls to Triple Zero did not connect. It referred 170 of them to state police. Seven people reported that they had needed assistance. "The volume of these welfare checks was higher than we expected and it has prompted us to investigate further," the company's chief financial officer, Michael Ackland, said.

The regulator's own statement identifies the structural problem at the centre of the case. ACMA said it had been engaging with "Telstra in its capacity as both the network provider and the Emergency Call Person". Telstra is the contracted operator of the national Triple Zero service. It is also the carrier whose network went down. The company under investigation and the company that runs the emergency line are the same company.

ACMA is examining compliance with the Telecommunications (Emergency Call Service) Determination 2019 and the Telecommunications (Customer Communications for Outages) Industry Standard 2024. The maximum civil penalty for failing to follow the Triple Zero rules is $30 million per contravention.

The recent record suggests what that maximum is worth in practice. In November 2024 Optus paid a penalty of more than $12 million after ACMA found 2,145 people could not reach emergency services during its 2023 outage and 369 welfare checks were never done. A month later Telstra paid more than $3 million over a 90 minute disruption to Triple Zero call transfers in March 2024, which ACMA found involved 473 breaches. When Optus failed again in September 2025, ACMA said it was "deeply concerned" that the company had broken "the same rules that the ACMA found Optus breached in 2023". That investigation is still open.

Mark Gregory, an associate professor at RMIT University, said the regulator would do nothing. "What is the ACMA going to do about it? Well, nothing, because the ACMA is the telcos' mate," he said. "They're not acting as a regulator, they're acting as best buddies with these companies."

Telstra has not fully explained the fault. Ackland said the problem was in nodes that keep time across the mobile network. "Time synchronisation in those nodes wasn't working as it should. We don't know why," he said. Chief executive Vicki Brady said on Friday it appeared to have been triggered by an error following a software restart, and that she was told about the outage at 7am, almost three hours after it began.

There were two faults, not one. The main outage was mostly resolved by 4pm on Wednesday. A second fault affecting some Triple Zero calls, which Telstra says came from the same software defect, was not fixed until 1.30pm on Thursday, roughly 33 hours after the first failure. Ackland said the nature of that second issue "only became apparent as we resolved the original outage".

A claim that a South Australian woman died after a failed Triple Zero call, raised publicly by Liberal senator Kerrynne Liddle, was ruled out by South Australia Police on Friday. Police said the woman's partner found her unresponsive after a medical episode, a neighbour called Triple Zero on a Telstra mobile, and an ambulance took her to hospital, where she later died. Police said the partner had separately been unable to reach relatives from the hospital, and that this may have been misinterpreted. Liddle apologised, saying her concerns were "based on information available at the time".

Anika Wells, the Communications Minister, said Telstra "has a lot of questions to answer" and that it would take the company "a lot of work and a lot of time to rebuild that trust with Australians". On Wednesday she had put it more bluntly: "There's a reason telcos are the least trusted industries in Australia. It's because of days like today."

The rules Telstra is being tested against are already under review. In March the government began an examination of the entire Triple Zero regulatory framework, led by the Triple Zero Custodian, a role created inside the Department of Infrastructure in March 2025 after the 2023 Optus outage. Wells said at the time that about 85 per cent of Triple Zero calls now come from mobile devices "yet much of the regulatory framework for the service was designed for a fixed-line world". That review is not due to report to government until March 2027.

Telstra has apologised. It has not announced any compensation scheme for affected customers. ACMA has not said when its investigation will conclude.