Due to some limitation somewhere between iOS and Fi, you can't hotspot an iPhone on Fi outside the United States.

It works fine on any phone within the U.S., and it works fine overseas on any Android phone (whether 'designed for Fi' or not). But you cannot tether or hotspot with iPhones overseas.

Oddly in my iPad the "Data only Sim" allows me to do hotspots overseas.

It may be the difference between the iPhone and iPad.

If my data SIM worked outside the US, I could test that. Sadly, it does not. If I ever get around to having Fi replace it, I'll test it :D

When I tested it with my 'real' SIM in an iPhone a couple months ago, tethering/hotspot appeared to activate but wouldn't work.

We've definitely had many different experiences with international use of regular and data-only SIMs and tethering, especially with iOS devices.

My understanding was that no iOS device can tether with either type of SIM, but that many Android devices, and more likely Fi-specific devices should be able to tether with either.

But I'd love some clarity on all of this.

The only device I have been able to make worth as a hotspot is a Moto X4 (Android, and Fi-specific). My iPhone and iPad won't do it - the option just never becomes active.

Interesting in that when I had tmo I could use wifi calling in Thailand but can't with Fi - I guess this is a limitation with a "non fi" phone rather than a limitation of their partners then?

I didn't mean that my phone worked on wifi (which of course it did) but that I was able to turn pause off while on wifi but not if I was not connected to wifi (I'm not sure if that is normal - since I've never done it before and was in Japan)
How were u able to reach customer service while paused?

sorry, I misunderstood your question. When I first resumed service I did it on my laptop from my house. I then went to use the phone outside of wifi and when I dialed it told me there was a problem with my account and sent me directly to customer service. Later when I was back in wifi I could make calls over the internet but when I turned wifi off and tried I went directly to customer service. Sometime mid afternoon yesterday everything started working fine on both my phone and my data sim in my ipad.

I had no problem tethering outside the US with either of the crappy beater Android phones (Nokia 3.1 and a Moto G5, neither of which are Fi-specific) that I've had in my kitchen drawer to lend to guests. I used my 'real' SIM but the data SIM should be the same assuming yours actually works overseas unlike mine.

https://support.google.com/fi/answer/6330195?hl=en

But I agree that people have reported that it works, so who knows.

Not being supported is not the same as not possible when it comes to Fi.

People have been using iPhone, with some limits, for years even though IOS only recently become supported, still with some limits.

Thanks - were u in the US? I wouldn't have had any way to contact cs or correspond with Fi from Japan unless I had a wifi connection -hence my question. When I tried to resume service I just got either nothing or an error message (can't remember), but when I connected to the airport wifi I resumed without problem - I think this was during the time people were reporting outages.
Is it usual to be able to resume outside the country without having a wifi connection?

I was in the us. If you go to the fi website and go to support you can request a call or chat.

Thanks - that only works if you have wifi if the phone isn't working ;) Good to know since I don't always have wifi 24/7 when out of the country

Exactly. "Is not supported" means "we make no effort to stop you, and it may or may not work, but don't bother calling us if it doesn't."

My data SIM works fine in the US, and I have definitely used it for tethering with no trouble.

Welp, after a brief stint with T-Mobile, I'm back on Google FI with my iPhone. This time officially "supported."
T-Mobile sending me threatening text messages when I dared to use the Global Plus roaming I paid $50 a month for on top of my $70 bill was the final straw.

PS. I can confirm that the Data Only sim allows tethering overseas. Works fine in my iPad Pro as hotspot. That said, in the iPhone my primary voice/data sim (when I last tried) tethering doesn't work internationally. Anyway, glad to be back.