The 3G switchover could be delayed if a working group of telecommunications heavy-hitters fails to iron out a technical glitch preventing some mobile phones from making emergency calls.
Nearly 750,000 mobile phones may not be appropriately configured to contact emergency services on the 4G network, based on industry estimates.
The worry is many users may not realise their devices cannot dial triple zero as they will otherwise function normally for other voice calls and data.
“Supporting Australians’ access to triple zero is critical," Communications Minister Michelle Rowland said in a statement.
“This new working group will ensure industry better co-ordinates efforts to identify and contact impacted customers, improves the accessibility of public-facing information and contact points, and provide regular advice to government on the number of potentially affected devices and customers in the market."
The phase out of the slower 3G mobile network is scheduled over the course of 2024 and started with TPG's network in January.
Ms Rowland said she was prepared to use regulatory options if the public interest warrants it, including "delays to planned switchovers".
Telstra, Optus, TPG and the peak industry body have been asked to join the working group.
Providers are already reaching out to customers likely to be affected, including those with older 4G models, devices bought overseas, or handsets purchased via the "grey market".
The government said telcos were best placed to assess whether devices were vulnerable to the technical error and consumers were "strongly advised" not to test call triple zero.
Opposition communications spokesman David Coleman said the government had been caught flat-footed in its response to the looming triple zero issue.
"Last November, the Australian Mobile Telecommunications Association warned of the risks in accessing the 000 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?"
He welcomed the establishment of the working group .
"But they’ve been caught napping on this and have failed the transparency test amid the Optus 000 crisis."
