Just had a long conversation with T-Mobile USA.
To have 100% Wi-Fi calling (WFC) you can do the following on any phone, I am listing for Samsung and iPhone.
- Switch on Airplane mode.
- Switch off location.
- Switch on Wi-Fi Calling.
- In Wi-Fi calling select “Never use cellular”.
- Switch on the Wi-Fi and connect to the internet.
iPhone: Everything is done thru Home Screen -> Settings
- Turn on Airplane Mode.
- In Phone, turn on Wi-Fi calling
- Turn on Wi-Fi and connect to the internet.
In Wi-Fi calling the phone connects over Wi-Fi to the T-Mobile Server in the USA, regardless of where you connect from.
When you have Wi-Fi calling (WFC) switched on and you are not physically in the United States, Canada or Mexico:
You call from a Simple Global Country to another Simple Global country, including the country you are roaming in: Charge $.20 ( The charge is same for cellular, means you are roaming on the partner GSM network, it will be the same). Even if you have Stateside International, that will not work. Phone is geo-located out of USA and thus you are basically gifting the $15 to T-Mobile for that period.
You call the USA, Canada or Mexico. Charge = ZERO cents.
This is great when you have long calls to those countries. Here while cellular would have costed you the same 20 cents/min even to USA, Canada and Mexico.
When I Wireshark (that is catch data packets using a PC), I see that all the time the data goes to T-Mobile, so where is the difference for T-Mobile?
The client (the phone) sends the information to T-Mobile using the internet and T-Mobile server completes the call, be you in USA or out of it. The call from T-Mobile onwards to the destination completes the same way. You wherever in internet coverage send the data to T-Mobile the same way.
I think these companies are now going to Verizon way. That is a sure shot way to lose customers.
VONAGE works the same way. Using the Internet as in Wi-Fi calling, the Vonage adapter connects to the central Vonage server and server connects the call. I never did and will never a charge up from Vonage even though it geo-locates me in a foreign country. Their Extensions app is great too.
My understanding was that when on Wi-Fi calling I am "As good as being in the US". The phone connects directly to the T-Mobile server no matter you connect from USA/Mex/Can or any other country.
T-Mobile and Sprint now charge you $.20 if you call a third country on WFC while roaming. Nexus !!!!
So long as they can geo locate you they charge. VPN will help I guess. I have to experiment. So, when you are roaming in a partner country do not run for a Wi-Fi hotspot because they charge the same $.20 if you’re not calling back to the US Canada or Mexico.
Very very very strange billing practice.
Wi-Fi calling is to me an EXTENSION OF THE T-MOBILE towers. This is so much bull and sheer greed in not honoring the calling plan as when I am Wi-Fi from the Moon, I am on T-Mobile network.