Telstra has delayed the shutdown of its 3G network amid concerns it may stop customers across Australia making emergency calls.

The national telco says it will now switch off the network on August 31 – two months later than planned – to ensure customers have upgraded their devices.

About 400,000 devices in Australia are 4G enabled but still rely on the 3G network to make triple zero calls.

“If you’re still using an impacted device after August 31, you won’t be able to call triple zero for emergency help,” Telstra CEO Vicki Brady said in a statement on Monday.

“We know some of our customers are still working through the steps they need to take to upgrade their devices.

“That’s why we’ve decided to provide more time and further support.”

Federal Communications Minister Michelle Rowland warned customers their device may appear to be operating normally after August.

However she said if they don’t upgrade, customers will find out it isn’t working properly when they make an emergency call.

“Australians may only realise there is an issue with the device when they can least afford it,” Rowland said in a statement on Monday.

Affected devices include mobile phones, landlines, farm machinery and medical devices.

Rowland welcomed Telstra’s decision to delay its planned 3G shutdown.

“Ensuring that more Australians have visibility and an understanding of the 3G switchover is critical to managing it in a safer way,” she said.

The federal government has set up a working group featuring Telstra, Optus, TPG and the Australian Mobile Telecommunications Association ahead of the 3G shutdown.

“The government will keep working with…the working group we helped establish to ensure impacted Australians understand the steps they need to take before the switchover occurs,” Rowland said.

Shadow Communications Minister David Coleman has slammed the government’s management of the shutdown.

“This decision underscores Minister Rowland’s hapless handling of the key issue that some 4G phones will not work after 3G shutdown,” he said in a statement.

The shutdown delay has been welcomed by rural Australians, especially farmers with machinery operating on the 3G network.

“With many farmers often working alone and a long way from help, switching off the 3G network without proper community engagement and support would spell disaster for many in the bush,” NSW Farmers Rural Affairs Committee Chair Deb Charlton said.

But she said more needed to be done by Telstra to educate and support rural Australians before the change.

“Connectivity is a critical tool, and so we can’t spare any time or expense when it comes to keeping our rural and regional communities connected and safe moving forward,” she said.

Customers who have affected devices will hear a message on outgoing calls to remind them to upgrade.

There is also an SMS tool where customers text ‘3’ to 3498 to find out if their handset is impacted.

– AAP