During the outage, a man in his 50s from the Melbourne suburb of Fitzroy suffered a cardiac arrest and later died after his family tried calling triple zero four times before being able to get through.

Danny Hill, the Victorian Ambulance Union secretary, told this masthead at the time that the outage caused chaos for paramedics.

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“It’s fairly clear that, yes, [the outage] played a role in the delay,” Hill said at the time. “Whether it played a role in the outcome of the patient is impossible to know.”

Brady said that Telstra reproduced the CLI issue in its lab environment and has issued software fixes to improve its systems. She said CLI was brought down by requests from internet-connected medical alert devices that overwhelmed the system.

“At the time of the incident, these devices were not making calls, but registering on our network in preparation should they need to do so in the future,” she said.

“This would not ordinarily cause an issue, however on this occasion it coincided with other system activity that resulted in connections to the database to reach the maximum limit. This triggered an existing but previously undetected software fault, which in turn caused the platform to become unresponsive and not able to recover on its own.”

Brady said she was personally overseeing work to implement improvements identified through the investigation.

“Let me reinforce that the series of failures that occurred on March 1 are unacceptable. The Australian public rely on triple zero in their times of greatest need, and we let them down by not being prepared enough for the situation,” Brady said.

“As CEO of Telstra, I apologise to everyone who tried to call triple zero during this issue, and in particular, the family of a man who suffered a cardiac arrest and tragically passed away.

“I want to reassure the Australian public that we have worked quickly to understand what occurred, learn from our mistakes and put in place improvements so that all Australians can trust that triple zero will be there to support them. ”

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Brady took the reins at Telstra in September 2022, and before then served as its chief financial officer.

Earlier this month, Australia’s communication watchdog, the Australian Communications and Media Authority (ACMA), launched its own investigation, which remains ongoing. The regulator said it would focus on Telstra’s obligations as the Emergency Call Person to transfer emergency calls to police, fire, and ambulance services.

Those findings will be made public.

Australia’s triple zero system is under scrutiny amid multiple recent failures. As this masthead first reported, there are concerns that nearly 1 million mobile phones will be unable to call triple-zero emergency services when the nation’s 3G network is switched off this year.

Meanwhile, during last year’s mass Optus outage, more than 2000 Optus customers were unable to get through to triple zero over a 16-hour period.

Then-Optus chief Kelly Bayer Rosmarin told a Senate inquiry last year that more than 200 triple-zero emergency calls were unable to connect during the November 8 outage, then revealing in January that the real number was more than 10 times higher.

“We don’t manage the triple-zero system. It’s a very complex system that involves all the carriers … We’re still investigating that, and we’re really happy that the ACMA has called an investigation into why this did not work,” Bayer Rosmarin said at the time.

Bayer Rosmarin resigned days after the outage, and Optus is yet to appoint a replacement.

The ACMA is also currently conducting an independent investigation into Optus’ compliance with triple-zero regulations.

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