The looming 3G closure has been delayed, in part due to public safety concerns surrounding the effects of the shutdown.
Australians are being urged to upgrade their mobile phones and check their medical devices as Telstra and Optus jointly announced the 3G network shutdown would be pushed back to October 28.
Both telcos had been preparing to switch off from the end of August but a recent Senate inquiry confirmed thousands of phones would not be able to make triple-zero calls after the shutdown.
The inquiry was also told critical medical equipment, personal cardiac alarms, EFTPOS machines and waste and water infrastructure could be cut off.
All telcos have a service for customers to check the status of their device by texting "3" to the number 3498.
~ with AAP