Originally Posted by
boerne
I always leave roaming on for our 2 Pixel 3 phones in the US or out. Does not seem to change the bill at all. I did have to switch to 3G in Paris last year. I also had problems in Copenhagen 2 years ago. When that happened i put the dialer codes in a Google Keep file. Link here.
https://arkienet.com/2018/01/google-fi-dialer-codes/
You might also have a look at the ‘Fi Switch’ app