On Monday 27 July at 12:00 pm (noon) AWST, a national emergency alert (AusAlert) will be tested. Every phone will sound a loud siren and vibrate for about 10 seconds – even on Silent or Do Not Disturb.
If you keep a hidden phone to stay safe, switch it fully off (or use airplane mode) at least an hour before and keep it off for at least 24 hours afterwards.