The telco that powers about 25 million mobile services across the country confirmed on Wednesday morning it was looking into the issue impacting "some mobile calls and data connections".
Minister for Emergency Management Kristy McBain said Telstra had informed the government the network disturbance has had a wide-ranging impact, including on public transport.
"The Australian government has been advised by Telstra that there is an outage affecting a large number of mobile calls and connections," she said in a statement.
The outage is also affecting triple 0 calls in Western Australia.
"A Telstra outage is currently affecting customers nationwide, impacting their ability to make phone calls, including calls to Triple Zero from Telstra services," the Western Australia Police Force said in a statement.
"If you are affected and do not have access to an alternative mobile or landline service, police recommend making arrangements with a neighbour, family member, or friend so you can access a working telephone in an emergency.
"Police communications systems are not affected."
Ms McBain also confirmed the service disruption has brought all Victoria's regional train services to a halt, leaving thousands of passengers stranded in the morning midweek rush.Â
"The V/Line network has been impacted by the nationwide Telstra outage," a spokesperson told AAP.
"This has resulted in significant impacts to our passengers this morning with no trains able to run on the V/Line network."
A very limited coach replacement service is in place with commuters asked to avoid travel until further notice.
Across the border, Transport for NSW said trains are not running between Newcastle and Maitland on the Hunter Line due to "an external telecommunication issue".
Trains are also not running between Campbelltown in southwest Sydney and Moss Vale/Goulburn.
Eftpos machine company Tyro also reported that its transactions have been hampered without specifically naming the provider.
"We're aware of an issue with a national telephone network provider and that some customers may not be able to connect to the 4G network right now to process EFTPOS transactions," it said on its website.
Telstra posted on social media platform X: "We're on it and will share an update as soon as it's fixed. Thanks for bearing with us."
But several customers replied expressing their frustration.
Telstra asked users to restart their devices as a temporary fix.
More than 7500 customers reported the network disturbance on online monitoring platform Downdetector.
The latest outage comes after other telecommunications giants Vodafone and Optus experienced recent gaffes that proved fatal.
In June, Vodafone customers were left with intermittent reception and data issues across Australia.
The telco said customers who could not access the network were able to use triple zero by connecting to other available mobile networks.
Two deaths have been linked to an outage at Optus in September 2025, which lasted almost 14 hours and affected hundreds of calls in four states and territories.
New rules were handed down by the Australian Communications and Media Authority in March forcing telcos to publish when the outage started and when it was restored in detail as well as the cause.
On Wednesday, Ms McBain said that, like all telcos, Telstra must notify customers and emergency services of any major outage.
"Australian phones are also required to fall back to other networks for 000 access," she said.
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