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.
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/