Please tell us some basic information before asking for help:
Model Name: ROG 5S
Firmware Version: 31.0810.1226.91
Rooted or not: Not rooted
Frequency of Occurrence: Ongoing
APP Name & APP Version (If your issue relates to the app): VoLTE
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
ROG 5S 512GB model in Australia.
When it was on Android 11, special code was required to enable VoLTE (Shows as "Call on 4G" in setting) - VoLTE did not work. Network drops from 5G to 3G when on call.
After upgraded to Android 12, "VoLTE" option is available in setting without special code - VoLTE still does not work.
Some reported that VoLTE works without issue in Australia with Telstra (Telco).
My previous devices such as iPhone 11Pro Max, 13 Pro Max, Galaxy Z Fold 2 and 3, Pixel 6 Pro had no issue with VoLTE with same SIM card with same service provider - Telstra.
Can someone confirm if this is the issue with the device or VoLTE does not work with Telstra? Because VoLTE works with Optus.