Be very careful with imported mobiles from now on as the government has basically told Telcos to soon not provide services to any phone they don't think can do emergency calling (000) on all the networks.
https://minister.infrastructure.gov.au/rowland/media-release…
Telco providers will also have to identify where an end user’s mobile device is unable to access Triple Zero, to notify those customers, and refrain from supplying carriage services to those devices.
https://www.legislation.gov.au/F2024L01103/asmade/text
6.(2)(b) where an end-user’s mobile phone is unable to access the emergency call service using either the provider’s own network or the networks of other carriage service providers who provide carriage services to the public, the carriage service provider is:
(i) to notify the end-user that the mobile phone is not able to access the emergency call service;
(ii) not to supply carriage services to the end-user in connection with that mobile phone;
EDIT And it has started with Optus ( https://www.optus.com.au/support/mobiles-tablets-wearables/i…. ):-
To keep you safe Optus will not support any new phone that does not meet the above standards. If you recently connected or re-connected a non-compatible phone on our mobile network, then your phone will not be supported from 10 September 2024.
If you receive an SMS, email, call or letter from us about this change, then you immediately need a new device to stay connected.
You will not be able to make or receive calls, text or use mobile data to browse the internet from an unsafe mobile phone from this date.
EDIT Optus existing customers ( https://www.optus.com.au/content/dam/optus/documents/for-you… ):-
from October 2024, any Triple Zero Impacted device already on the Optus network will stop working.
TL;DR Any mobile the telcos don't think can correctly do emergency (000/112) VoLTE calling on all three networks will soon be blocked from working on all three Australian networks (excludes short term roamers).
Yeah, that is regards to the closing of the 3G network and imported 3G only phones.