Every decade or so, mobile networks move to a new generation. Here’s what 5G actually changes, why Australia’s 3G networks were switched off, and why some older phones were left unable to call triple zero.
Mobile networks have evolved in generations, each bringing new capabilities.
1G, in the 1980s, carried analogue voice calls. 2G introduced digital calls and text messages. 3G, from the early 2000s, made mobile internet practical. 4G, from around 2011, delivered fast enough speeds for streaming video and apps. 5G, launched in Australia in 2019, is the latest.
What 5G does
5G offers faster download speeds than 4G, and much lower latency, the delay between sending and receiving data. It can also handle far more connected devices at once.
For most phone users, the difference is mainly faster downloads in busy areas. The bigger potential is in other uses: connecting factories, mines and ports, remote-controlled machinery, smart city sensors and home internet. 5G home internet has become an alternative to the NBN for some households.
5G uses a range of radio frequencies. Lower frequencies travel further and through walls, while very high frequencies, known as millimetre wave, are extremely fast but cover only short distances.
Why 3G was switched off
Radio spectrum, the airwaves mobile networks use, is limited. Keeping old networks running takes up spectrum that could be used for faster, more efficient 4G and 5G.
Vodafone switched off its 3G network in late 2023. Telstra and Optus followed in October and November 2024, after delaying their plans.
Phones that relied on 3G for calls stopped working for voice calls, and the telcos contacted customers to replace them.
The triple zero problem
A bigger issue emerged before the shutdown. Some older 4G phones were set up to fall back to 3G for emergency calls, because they didn’t support 4G calling on Australian networks. After 3G closed, they couldn’t call triple zero.
Telcos identified hundreds of thousands of affected devices, and new rules required them to block phones that couldn’t make emergency calls from their networks.
Concerns about triple zero reliability grew in September 2025, when an Optus network failure stopped hundreds of emergency calls from connecting in several states, and several deaths were later linked to the outage. It led to investigations, calls for tougher rules on telcos and changes to how outages are reported.
What’s next
Telcos are expanding 5G coverage and building “standalone” 5G networks that don’t rely on 4G. Satellites are also being used to fill gaps in regional areas.
Work is under way internationally on 6G, expected around 2030, which promises even faster speeds and closer integration with satellites and AI.
