Australians woke up this morning to a major outage affecting Telstra, the largest telecommunications network in the country. But mobile phones weren’t the only thing knocked out of action.

Some EFTPOS payment services, taxi payment systems, electric vehicle charging platform Chargefox, and public transport ticketing in Canberra were all affected. There have been conflicting reports over whether Triple Zero calls were impacted, as they were in a recent Optus outage.

Read more: How do Triple Zero calls actually work? A telecommunications expert explains

Most notably, train services were affected in Victoria and New South Wales. Victoria’s regional train system, V/Line, suspended services across all lines due to the national Telstra outage.

As of Wednesday mid-morning, there has been no estimated time for when trains will start running again, and limited coach replacements are available. With the outage having started about 4.30am, this threw the morning commute into chaos for many.

But how does a mobile network crash affect trains? Let’s look at the underlying tech connections.

How do trains use a mobile network?

Trains have roof-mounted antennae that connect them with control centres. Voice and data communication between trains and control centres takes place on........

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