@undrwater HI, Could you read my (wrongly addressed) reply to vverve, asking about your use of Nord N10 in USA, and actually using VoLTE ?
Also, I am often in rural area, and mostly use WiFi calling (which, from what I understand, shares code with VoLTE).
Have you tried WiFi calling ?
Any other info or suggestions, before I try to return recent Pixel 3A XL and buy a Nord N10 ?