One million phones are set to be cut off from calling Triple Zero when 3G is axed this year - here's how to check if yours is one of them

More than one million Australians may be unable to call Triple Zero when telcos shut off the 3G network in the coming months.

Telstra will close down its 3G network on June 30 while Optus is set to end the service in September. Vodafone switched off 3G for its customers last December.

While most phones currently in service primarily access 4G or 5G networks, there are an estimated three million devices including phones, EFTPOS machines, cars, security cameras and medical alarms still relying on 3G.

There are also now concerns for the roughly one million 4G handsets that are either old or were bought overseas and rely on 3G for calling emergency services.

These handsets use 4G for other services such as calls and texts but use 3G for phoning Triple Zero.

Communications Minister Michelle Rowland is speaking with a 'working group' that includes the major telcos every two weeks to come up with a solution.

'Supporting Australians' access to Triple Zero is critical,' she said last month.

'While the Government supports the safe switchover from 3G, it is important Australians are aware that some devices in the mobile market are not appropriately configured to contact emergency services on the 4G network.'

Shadow communications minister David Coleman accused the Albanese government of being too slow on the issue last month.

'Last November, the Australian Mobile Telecommunications Association warned of the risks in accessing the Triple Zero service with the closure of the 3G networks,' he said.

'So why has the Albanese government failed to engage properly on this issue until now?

'We welcome the fact that the government has finally woken up to the looming risks that many thousands of people will face in being able to call Triple Zero after the 3G networks close.'

Telstra on Monday shared a how-to video showing customers what to do if their devices are impacted.

'If you or someone you know is a Telstra customer, or have a device that uses Telstra's mobile network, simply SMS 3 to 3498,' they said.

'We'll respond to let you know if you'll still be able to use the device you're messaging from on our network, and whether you need to take any action.'

There are reportedly 113,000 Telstra mobile phone customers still using 3G.

Optus said it will directly contact customers with affected devices.

Editor and Tech Commentator for EFTM.com, Trevor Long, said the change should not worry anyone who's bought a phone in the last about five years.

'The bigger risk is to people with extremely old phones, which - despite 5G being five years old, and 4G being a decade more than that - don't even connect to 4G,' Mr Long said.

The shutdown is likely most concerning to those using medical devices which still use the 3G network, which Mr Long said is a big risk for 'connected medical devices.'

'Not just because they might be old devices but even more recent devices sold just five years ago might not have had 4G capabilities,' he said.

'So there's a risk people will think this doesn't apply to them because they only got the device five years ago, yet in fact they might be left with a device that simply fails to work at the most important time in a year from now.'