Telstra has apologised to customers, including those trying to call triple zero, after a widespread national outage halted trains in two states and hit thousands of businesses.

The telco, which powers about 25 million mobile services across the country, confirmed on Wednesday it was investigating the issue with thousands unable to make calls and access data on their phones from 4.30am.

Telstra chief financial officer Michael Ackland expressed regret for the outage, describing it as intermittent but widespread.

“At this stage, we do not know what the root cause was. I’d rather let the investigations play out,” he said in Melbourne.

He assured the public that triple-zero calls followed different settings and were not affected in the same way as other mobile calls, but said the telco had conducted several welfare checks.

“We can monitor all calls that are attempted and failing and we have been conducting welfare checks on those,” Ackland said.

“We are continuing to investigate every angle on where it may have impacted triple zero, if that has occurred.”

Communications Minister Anika Wells confirmed that some emergency calls did not connect on Wednesday during the Telstra outage.

Western Australian police said the outage affected triple-zero calls in that state.

“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,” WA Police said.

NSW Police said the wider triple-zero network was not affected but calls might not work from Telstra mobiles.

“If you try to call triple zero and can’t get through, we recommend using another device, a landline or Wi-Fi calling,” they said.

Queensland Police said the emergency call network in that state was fully operational.

“Impacted customers should check with their provider about what the outage means for them,” they said.

Telstra, which is Australia’s largest mobile network, said later on Wednesday morning it had made “good progress” restoring services. About 90 per cent of calls and data were flowing successfully.

“We know how much our customers rely on our network and understand just how much of a disruption this is to your day,” the company said.

“For that we’re so sorry. We’ll share further updates until all is resolved.”

The outage also affected other mobile companies that use Telstra’s network, including Aldi Mobile, Belong, Boost Mobile and Tangerine.

“Our wholesale mobile network provider Telstra, is currently experiencing a major outage, affecting over 100,000 services nationally,” Tangerine said in a social media post.

“In some cases, Tangerine customers have been able to restore their service by restarting their device. Please try turning your phone off, waiting a few seconds, and then turning it back on. This may not work for everyone.”

Emergency Management Minister Kristy McBain said the government was told the network disturbance had a wide-ranging impact, including on public transport.

She confirmed the service disruption had brought all Victoria’s regional train services to a halt, leaving thousands of passengers stranded in the morning midweek rush.

The V/Line network said no trains could run on the tracks. Limited bus replacements were available but commuters were asked to avoid travel until further notice.

Across the border, Transport for NSW said trains on its Hunter Line had also been affected. Trains were also halted between Campbelltown in south-west Sydney and Moss Vale and Goulburn.

Eftpos machine company Tyro reported its transactions had been hampered without specifically naming the provider.

Ackland insisted customers should still trust Telstra.

“Australia can absolutely have faith in its biggest telco, and that is Telstra,” he noted.

“We take these outages very, very seriously. Our investment in resilience and cybersecurity and redundancy in our network is significant, but it is a big and complex network.”

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 had intermittent reception and data issues across Australia. It said customers who could not access the network were able to use triple zero by connecting to other available mobile networks.

An Optus outage in September 2025, which lasted almost 14 hours and affected hundreds of calls in four states and territories, has been linked to two deaths.

-with AAP