Nationwide Telstra outage cuts mobiles, grounds V/Line and hits Triple Zero

A national Telstra outage knocked out mobile calls and data across every Australian state today, grounded Victoria's entire regional train network, and left some callers unable to reach Triple Zero.

The failure started about 4.30am.

Telstra chief financial officer Michael Ackland said the cause was a set of network nodes that keep time synchronised across the mobile network. When they failed, calls and data dropped out in waves.

Ackland would not put a firm number on how many customers were hit, saying it could be "tens of thousands" but was likely fewer. Telstra runs about 25 million mobile services and also carries Boost, Belong, Aldi Mobile and Tangerine, all of which went down with it.

By mid-morning the telco said just under 90 per cent of calls and data were working again.

The damage spread well past phones.

Victoria's entire V/Line regional rail network was grounded, with the operator blaming the national outage. Some NSW train lines were cut. Commonwealth Bank warned that some EFTPOS terminals had stopped working and told businesses to switch to an Optus connection. Canberra's MyWay+ transport ticketing went offline. In South Australia, 378 traffic signals dropped out.

Then there was Triple Zero.

Western Australia Police advised that some Telstra customers could not get through to 000. Communications Minister Anika Wells issued a statement following the outage, confirming some callers were affected and that welfare checks were being run on people who could not connect.

In a joint statement with Emergency Management Minister Kristy McBain, Wells said the core Triple Zero system stayed up and that connected calls flowed as normal, but that the Triple Zero Custodian had advised some callers could not reach the Emergency Call Person.

That the Custodian was in the room at all is the point.

It exists because of Optus.

On 8 November 2023, an Optus outage cut off more than 2,100 people from Triple Zero and the company failed to carry out 369 welfare checks. It was fined more than $12 million. The failure prompted a federal review by former regulator Richard Bean, whose 18 recommendations — all accepted — included standing up a Triple Zero Custodian to give the system end-to-end oversight.

Then it happened again, worse.

On 18 September 2025, a botched Optus firewall upgrade blocked hundreds of emergency calls across South Australia, WA and the Northern Territory. Three deaths were linked to the outage. Optus did not detect the failure itself — it was first told by the South Australian Ambulance Service — and staff who took early complaint calls did not escalate them. The company did not tell the Communications Minister about the fatalities for about 17 hours.

The Custodian was made permanent in law weeks later, on 31 October 2025, with new rules forcing telcos to report outages to the regulator and emergency services in real time, test Triple Zero during upgrades, and guarantee calls fall back to other networks. The maximum penalty for breaching the Triple Zero rules was lifted to $30 million.

Today was the first big test of that system.

Wells said the Australian Communications and Media Authority would conduct a full investigation, and that Telstra would have to account for how and why the outage happened.

Ackland said Telstra did not yet know the root cause.