Telstra has admitted to an "avoidable error" that led to a nationwide network outage impacting millions of Australians, disrupting emergency Triple Zero calls, and causing significant problems for train services and EFTPOS payments. The telecommunications company stated that the failure could have been prevented by a software update or better documentation, according to its submission to a parliamentary inquiry.

A GPS card within a device, repaired during scheduled maintenance, did not function as expected after power was restored to the network. This issue arose from an "intentional design change" made to the equipment to fix a previous fault, a change that was not adequately documented. Consequently, the maintenance team was unaware of the potential problem when restarting the device. A crucial software update that could have averted the outage had also not been applied.

"That is clearly unacceptable. If maintenance work can trigger this kind of outage, it suggests our controls were not good enough," Telstra stated. The company acknowledged accountability, vowing to investigate why the design change was not documented, the software update was not completed, and how to improve controls to capture and address known risks before they affect customers.

Telstra CEO Vicki Brady is scheduled to face questioning at a Senate inquiry regarding the incident. Greens Senator Sarah Hanson-Young criticized the company, suggesting that profits have been prioritized over consumer protection and calling for stronger regulations. "Millions and millions of Australians have been impacted by Telstra's bad performance, from Telstra's incompetence, and we'll be asking questions of the CEO and the executives about that today," she told reporters.

The outage, which occurred last week, left thousands unable to make calls or access data. Approximately 80,000 businesses using an affected EFTPOS payment system experienced disruptions. Train services in Victoria and New South Wales were canceled due to severe network disruptions, drawing strong criticism from the federal government.

Telstra is accepting compensation claims from affected customers and small businesses. The company also conducted over 630 welfare checks on customers whose Triple Zero calls failed to connect during the outage. Brady has previously apologized, stating, "Last week we let you down, and I am sorry for that." Representatives from the Australian Communications and Media Authority and the communications department are also expected to provide evidence at the inquiry.