Can i use my phone in Australia

Apple iOS Upgrade to 26.1 did the trick !

Arrived in AUS last month and have been frustrated by SOS instead of reception bars on my iPhone since. Finally found time to speak to Smarty on a chat yesterday and they blamed Apple which didn't make sense to me at the time. 

My own AI assisted research tells me ... 

This issue is not exclusive to Smarty, but Smarty (and Three UK) users seem to be reporting it in higher numbers than users of other UK networks. The root cause is an Australian government-mandated blockade by Australian networks, not a failure of the Smarty SIM/eSIM itself. 

The Core Issue: "Triple Zero" Blocking

As of late 2024, Australia has shut down its 3G networks. To prevent people from having phones that look like they have signal but cannot actually dial 000 (Emergency Services), the Australian Communications and Media Authority (ACMA) introduced a rule requiring networks to actively block any phone that is not correctly configured to make emergency calls over 4G (VoLTE) on their specific network. (NB: people have sadly died due to this 000 issue in AUS so it's not just red tape for the sake of it)

The Impact: If your phone/SIM combination does not send the correct "VoLTE Emergency" handshake to the Australian network immediately upon arrival, the local network will block your device completely. You will see "SOS Only" or "No Service."

You can check if your mobile is blocked on Telstra's network by searching for "3G-Network-Closure-Blocked-Devices-Checker" (actual link not allowed apparently).

My iPhone 12 mini has, until yesterday, been stuck on iOS 17 even with auto-updates selected. When I went in to check what version it was yesterday I was offered, for the first time, the opportunity to install iOS 26.1, which I took. My Smarty eSIM now works in AUS, no issues. So it seems Smarty's advice that Apple needed to do something was correct, though they could have added the need to check for any iOS updates when in AUS.

I should mention that I have both a UK Apple ID and an AUS Apple ID. When in AUS I use the latter, which is maybe why I was suddenly able to jump from iOS 17 to 26.1. 

Anyway, I hope this helps my fellow Smarty users while they enjoy the lucky country!

Stephen_2289888 Have you looked at the list of suggested articles at head of the page of posts?

You need to change settings on the phone first and then add a load of money to pay for all usage. Take a lookout the Price Guide for costs of International Roaming.

Possibly best to buy a local sim over there, or an e-sim if your phone accepts them. Also free wifi would allow you to call people on WhatsApp or similar.