Indigenous Australians may have phones that won’t connect to triple zero after the 3G network shuts down later this year.

Optus will shut down from September, while TPG Telecom/Vodafone began its closure in January.

Though the end of 3G has been flagged for years, there are up to 530,000 Australians with devices incompatible with the 4G network, according to the latest industry figures.

Users may not realise their phone is configured this way until 3G is switched off.

The telcos have been contacting affected customers to advise users to take action.

Both Telstra and Optus have launched a service for customers to check the status of their device by texting “3” to the number 3498.

Optus executive Harvey Wright said the company has ramped up its efforts to keep users connected, launching the text service this week.

Customers can also be assured 3G will not be switched off where it is the only available network until 4G is made available, Mr Wright said.

“The number of sites like that are very small and we’re confident that we will be able to maintain the coverage that we’ve got in both metro and regional throughout this process,” he told AAP.

The 3G shutdown will also affect medical devices, farm machinery and EFTPOS terminals.

Graeme Hughes, a consumer commentator and director of Griffith University’s Co-Design Lab, said those devices were of particular concern.

“I would like to see an extension of the shutdown,” Mr Hughes told AAP.

“There needs to be a collective approach, with co-messaging from government and Optus and Telstra … which enables the consumer to really understand what they need to do to not be at risk.”

AAP