Fi working great in UK (London and Leeds). I have a new phone (Pixel 4a/5G) and it wasn't working well in Spain (multiple cities) in November/Dec. So either Google update some software or it is a Spain glitche. Their CS thought it was an app issue (one app causing an issue, but I have same apps here as there).

Hard to believe it's a Spain issue... but there you have it.

Fi works pretty much everywhere in Italy as well. I just spent 9 months living there and had no issues. I also like that they did not cut off my service even though I was only paying $20 per month for the number and getting my data from an Italian sim card. It's so convenient to just land anywhere on earth pretty much and have your phone work. Coming back to America was a breeze as well.

Did anyone else not get charged the base $20 fee this month? I have one line with four data only SIM and this month I only got charged for the data. Was trying to figure out if it was some change or so just a bug or what.

Hmm, yeah, same here.

Just one line, voice+data, only charge was about $5 for data (and $4 for taxes).

I saw something on a Google Fi facebook group pop up in my news feed, about some customers who had weather-related service outages not getting charged this month.

Could be I guess?

But back in September, they gave me a $20 credit due to impact from Hurricane Ida. In that instance, they emailed about the credit in advance, and on the bill, there was the usual $20 charge and a separate line item with the ($20) service credit. This time, no email or other notice, and no separate credit, just the monthly charge omitted.

And our weather and service here in Louisiana the last month has been fine.

Working great in France, UK, and Italy. Didn't work so well in Spain or Lisbon. Weird that. Same phone, same toggled connections, same FI service.

If your phone supports eSim have a look at Airalo and Flexiroam for good options and better data pricing.

I understand most modern phones now support multiple
esims, but must be manually switched from one to the next.

My Mom is a UK resident, who visits the US a couple of times a year. She has a UK-based iphone that she uses there, and a separate ancient Republic Wireless phone (US number and plan) that she uses when she is in the US, and for wifi calling to/from US friends when at home in the UK. Data usage is minimal. But the Republic phone/plan won't be supported after the end of this month.

Unfortunately, she's not technical enough to swap sim cards when she travels.

It seems like the ideal, simplest solution might be to add her as a second line on my Google Fi plan, and get her a new phone. She's have US service when here, and still be able to make wifi calls for free. But I'm wondering about Fi's rules that you must be US based.
- If she's only using the phone in the UK when on wifi at her home, she wouldn't be using any international cell minutes or data. Would Google still care?
- Any data points how Google handles multiple line accounts, where only one line seems to violate the service location restrictions? It wouldn't be too big a deal if at some point they cut off her service, but I don't want to put my own Fi service at risk.

Does anyone know how to check the call rate FROM a country (Maldives) TO the US?

This page seems to be FROM the US TO a country. Maldives is 70 cents per minute on wifi.

Meanwhile, This page says cellular calls are 20 cents per minute (across the board?). Does that mean it's cheaper to make cellular calls than wifi calls in Maldives to the US?

VoIP (wifi or cell data) calls to the U.S. (and Canada) are free. All VoIP calls are charged at the rate in your first link regardless of where you are. Cell calls from the U.S. are also charged at that rate.

Cell calls made from outside the U.S. are charged at 20c/min regardless of origin and destination, which means that sometime's it's cheaper to force wifi and sometimes it's cheaper to pay 20c/min rather than the "standard" rate to some less developed and/or more remote places.

How do I (or can I) trigger VoIP on my Google phone that confers free calls to the US? Sounds like it's not the same as calling over Wifi.

VoIP is any call made over the internet, including a call made over wifi with Fi (and also including a call made via cell data).

Until a couple years ago, you could force Fi to use VoIP with or without wifi by making the call from Hangouts. Now that Hangouts is deprecated, you can force wifi calling by putting your phone in airplane mode but AFAIK there's no way to get Fi to make VoIP calls on cell data anymore.

An effective but inelegant workaround is to also have a Google Voice number. GV is easily forced to use VoIP. I found for my use case it was better just to use GV, ditch Fi altogether, and buy cheap eSIMs where my home carrier didn't cover.

I suspect that this would be fine. She will not be alone in being based outside the US and using Google Fi as the US phone - there are many posts here of people doing just that. I don't know how much Google will audit usage but I strongly suspect that the only usage they will care about is usage of cell towers, as that's what will cost them. If your mother's only, or predominant, cell tower usage is in the US, I doubt that she or you will have a problem.

Updated Fi Plans
 

https://support.google.com/fi/?p=pls_upd