Please tell us some basic information before asking for help:
Model Name: ROG II 12GB/512GB
Firmware Version: Latest
Rooted or not: Never
Frequency of Occurrence: Aways
APP Name & APP Version (If your issue relates to the app): Phone
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.
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Without VoLTE, the legacy 3G network is necessary to call.
Here in Brazil, no VoLTE in any operator for my super 12/512GB ROGII, but yes for basic devices from other brands.
It's beginning, see:
Verizon will shut down its 3G network next year, following multiple delays.
https://www.xda-developers.com/verizon-shut-down-3g-network-2022/