Hi Tom.
I also have a stock Android 10III and it will not do VoLTE or VoWiFi on 2degrees,Voda or Spark - it’s not a Sailfish issue. 2degrees has turned off 3G now, and mine is now useless for phone
Btw, there is no listed Lineage for 10III.
Sony did not install any .mbn files for NZ in these phones, because they weren’t selling them here. There is a dir for AU, but not NZ I have not managed to find such a file. I did ask about adding them in Community meeting on 11th September 2025 - #2 by crun but I got no answers to any of those questions.
I don’t know if the 10IV or 10V work in NZ, but 10VI allegedly does.