Tasmania will be the first state to experience this shutdown, with the rest of Australia following suit by November 4.

Telstra is initiating the transition in Tasmania, a strategic move since it does not share borders with other states.

This shutdown will impact not only mobile phones but also other devices such as tablets and dongles that rely on 3G connectivity.

Many customers may still be using devices that depend on 3G or 4G devices that revert to 3G for emergency calls.

Optus has proactively reached out to affected customers, sending over 10 million messages with instructions on how to upgrade to compatible devices.

To assist customers during this transition, Optus is offering a range of discounted and zero-cost devices amid the ongoing cost-of-living crisis.

Approximately 59,000 devices in Australia must be updated by the weekend to ensure they can make emergency calls.

In line with new federal legislation, Telstra will begin blocking devices that cannot call emergency services, known as triple-0, starting next week.

Customers can check if their mobile device will work after the 3G shutdown by sending an SMS with the text '3' to 3498.

Starting Monday, October 28, Telstra and Optus will shut down their 3G mobile networks to enhance the capacity, speed, and reliability of their 4G and 5G services.

It's worth noting that Vodafone has already completed its own 3G network shutdown, setting a precedent for the industry.