The Telstra outage is a stark reminder of the widespread effects of single system failures

The network disruption – which brought trains, traffic lights and Eftpos payments to a halt – raises questions about the resilience of services

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Wednesday’s national Telstra mobile outage serves as another stark reminder of how reliant on connectivity Australia now is, and how single points of failure can have widespread consequences across the country.

The nearly five-hour outage – which brought train lines to a halt, affected traffic lights, stopped Eftpos payments and even prevented people being able to charge their electric vehicles – was caused by what Telstra’s chief financial officer, Michael Ackland, said was time-keeping servers that feed up-to-date information to the rest of the network.

When the time appears out of sync across the systems, it creates problems.

“Lots of computer systems, they have to synchronise time. It’s one of the ways that you authenticate what’s going on in the network, and the time synchronisation in those nodes wasn’t wasn’t working as it should,” Ackland said at a press conference on Wednesday morning.

On Wednesday evening, Ackland revealed a “software defect” in an update had impacted Telstra’s time server, which keeps time across the company’s network systems. Its accuracy is vital to the running of the network.

It appears to be yet another example of a single issue at one company causing massive disruption in Australia.

As we saw in the 2024 global outage caused by CrowdStrike , the 2023 Optus national outage , and the 2025 Optus triple-zero outage , single system problems can have cascading effects across not just their own systems, but across the economy.

Outages are not uncommon elsewhere in the world, but in Australia they seem to hit with greater impact.

When it comes to mobile outages, it is hard not to see this as an issue with having just three mobile network operators in the market: Telstra, Optus and Vodafone. When one falls over, the impacts are widespread – particularly for Telstra, which has the lion’s share of customers and whose network is used by numerous smaller mobile companies.

Customers who left Optus after the incidents of recent years learned today that it’s not just an Optus issue.

It also raises questions around the resilience of services – both of the telcos and also the businesses and organisations that use their services.

The processes for governments to deal with these outages appear to have improved since the 2023 Optus national outage. On Wednesday, the federal government was on the front foot, checking on emergency calls with the new triple-zero custodian , which was planned after the 2023 Optus outage but only implemented after last year’s Optus triple-zero outage.

The government quickly responded to the outage, with the communications minister, Anika Wells, returning from leave to address the matter.

Wells acknowledged there have been some improvements, but put blame on the telcos for losing the trust of the Australian public. “There is a reason that telcos are the least trusted industry in Australia – it’s days like today,” she said.

“It is on all telcos to improve their systems to make sure that Australians can rely upon them when they need them most.”

The Australian Communications and Media Authority has been asked to investigate the Telstra outage, and the company has promised the communications minister to provide more updates on what caused it.

Hopefully, that will address what redundancy measures could be in place to prevent an issue like this occurring again – as well as what other potential issues they might safeguard against in the future.

Businesses, for example, could look into whether having multiple mobile connections is feasible.

It defies belief that rail operators might not currently use multiple mobile companies for their communications, so that if one goes down, they could fall back on another. But that may go to the other issue of connectivity: when Telstra has the best network in the country, could they rely on others in regional areas?

“As transport networks become more digital and connected, they need communications systems that can tolerate faults without bringing an entire network to a standstill,” says Hussein Dia, professor of transport technology and sustainability at Swinburne University of Technology. “That means reducing single points of failure through redundancy and ensuring there are alternative communication pathways if one system is disrupted.”

Dia says hospitals and airports already operate with this resilience mindset, and transport should take the same approach.

Adjunct Assoc Prof Graeme Hughes, of Griffith University, says policymakers should mandate multi-carrier routing for public transport and essential services, while businesses and households should keep cash on hand, enable wifi calling, and know how to switch a payment terminal to a backup connection.

Assoc Prof Mamello Thinyane, in the school of computer science and information technology at Adelaide University, suggests businesses should consider multiple types of connection such as fixed line and 5G across multiple service providers.

“What is for sure is that this will not be the last network outage in Australia … are we all going to put measures to ensure we are collectively more cyber-resilient going forward? ‘Til the next one.”

Josh Taylor is a technology reporter for Guardian Australia