Wifi calling while outside of US

I'm guessing what they are looking at from the website, is a little misleading.  At least from my understanding.  

https://www.t-mobile.com/support/coverage/wi-fi-calling-from-t-mobile#secondheading

The only section that really applies to WiFi Calling, is the first section that is note worthy.  Once the background color changes, that applies to roaming, not WiFi Calling.  At least that is my interpretation of it. If you scroll down to the end of those, there is one message that seems pretty clear on the subject. 

“Prevent unexpected charges when traveling abroad

Ten en cuenta que, si tu conexión Wi-Fi se corta por un instante o si sales de su alcance, es posible que tu llamada se cambie a la red celular. This means unexpected charges if you're in another country."

I have never been charged for WiFi Calls made on my One plan or going even further back to when I was a prepaid user that traveled to the UK and EU at least once a year for a couple of months at a time.  However, when traveling outside of North America, I always keep my phone in Airplane Mode, then turn on WiFi, and enable WiFi only when I get to somewhere that has reliable WiFi for WiFi Calling.  

If charges appear on your bill for WiFi Calling use on your One plan.  I would personally dispute them with the T-Force Team via Facebook or Twitter.  

Another thing to be aware of is, that if a call drops off of WiFi Calling on to cellular, applicable calling rates will apply.  

Syaoran: right, totally get that…. But all the calls between 2 US numbers were stated as Wi-Fi calls on my bill.

(one person in Japan and one person in US: both US numbers.) 

so these calls should be free of charge, correct? 
nobody called Non-US numbers. 
 

From my understanding  calls that are 100% over WiFi are treated as calls made within the US.  Your plan decides whether or not those calls have a charge.  As an example, my T-Mobile One plan includes unlimited calling in the US, Canada, amd Mexico.  When I visit the UK, I put my phone in airplane mode and use WiFi Calling to call the US, Canada, and Mexico because those WiFi calls are treated like they are originating from within the US.  

Syaoran: Thank you. That's what I am reading as well… but this is what Chat person from T-Mobile said to me. And they told me that I won't know if I will be charged or not until the billing cycle ends… (In 10 days.) 

does this chat make sense though…? It doesn't to me.

Mine is T-Mobile one plan. Unlimited calls and text as well. 

@Nalogirl  What did you end up getting charged?

There is this info here, too: https://www.t-mobile.com/support/coverage/wi-fi-calling-from-t-mobile

and by the way it reads, you should have gotten no charge.

But as so often, T-Mobile has a confusing plethora of information and employees do not know the intricacies of the pricing structures. See my post here also:

The safe thing to do is to use a VoIP app like Google Voice, FaceTime, Viber or Signal.

Nalogirl- we are in the same boat made calls to the us (also recieved which isn't very clear on T-Mobile) from another country and we're charged .25cents/min despite being in airplane mode and wifi. I think everyone on the thread should check their bill- we also have unlimited minutes on a magenta plan and got charged, seems like they charge whether you're on wifi or not, it is not only if you get bumped off wifi and being on airplane mode doesn't protect you! So outrageous