Telstra mobile network crashes nationwide causing transport and payment delays

Telstra's mobile network appears to be suffering a major outage across the country. (ABC News: Lucas Hill)

Telstra's mobile network has suffered a major nationwide outage, affecting potentially millions of customers and causing delays to public transport networks.

Some regional train services in NSW and Victoria have been suspended, and taxi passengers are reporting they are unable to complete payments.

Telstra says it is looking into the issue and will share an update once it is fixed.

Telstra's mobile network has suffered a major, nationwide outage, leaving potentially millions of Australians unable to make phone calls or access the internet.

The outage is also affecting payment systems and public transport across the country, with regional rail lines in NSW and Victoria and the ACT's MyWay+ ticketing system among those services affected.

Hundreds of traffic lights in South Australia are also affected, operating on basic programming rather than responding to traffic conditions.

The outage appears to have started early on Wednesday morning, with outage monitoring site Downdetector.com showing a large spike in reports beginning about 5am AEST.

Downdetector.com shows a huge spike in Telstra outage reports shortly before 6am. (Supplied: Downdetector.com)

Users of other mobile providers that operate on Telstra's network, including Boost, Aldi, Tangerine, Belong and Everyday Mobile, are also reporting outages.

However, the outage does not appear to be affecting all the telco's customers, with some reporting on social media that they are still able to make calls, access the internet, or both.

Calls to Triple Zero (000) should be unaffected by the outage, with calls being rerouted to use other providers' mobile networks, and emergency services in Victoria and the Telecommunications Industry Ombudsman have said this is the case.

Carol Bennett believes self-regulation within the telco sector is not working, and says there's a risk of more connection failures unless the government and its telecommunications regulator act now.

Police in NSW also said they understood the outage was impacting network devices, and some people might need to call Triple Zero using a non-Telstra device.

"Triple Zero systems are not affected, but you may not be able to reach Triple Zero if you are calling from a Telstra device," a NSW Police spokesperson said in a statement.

"If you try to call Triple Zero and can't get through, we recommend using another device, a landline or Wi-Fi calling."

A Telstra spokesperson told the ABC the company was "investigating an issue affe