T-mobile can push wifi calling ability to unlocked Galaxy S9?



    Samsung technical support is telling me that T-Mobile has the ability to push the wifi calling option onto the unlocked phone. Can someone please confirm? I would like to buy a dual sim version of the phone, unlocked.

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      • smplyunprdctble

        "push", no.


        However, it's probably already built in to the OS -- T-Mobile provided the code to the manufacturers MANY years ago, and it's their choice as to whether or not to include it.  Since Samsung provides a version to T-Mobile, I'd imagine the code is there.  But, T-Mobile cannot confirm whether or not it's there.

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          • amonra

            Thank you.  Samsung says it’s a carrier option and T-Mobile has to enable it... the setting is missing from the unlocked version.

              • smplyunprdctble

                I guess it means what they mean by "enable it"


                The information on what to connect to is programmed in the SIM.  The code execution should be in the phone kernel.  T-Mobile cannot change the phone kernel, so the code needs to previously exist.  The phrasing sounds like the coding exists and "enabling" it is within the SIM, but, unless someone else has the device, there's no way to vouch for it.


                I CAN tell you that you don't need a T-Mobile branded device to get WiFi Calling.  My last few devices were non-branded directly from Google (Nexus 4, 5, 5X, Pixel 2), and once WiFi Calling was built into Android (it was either part of N4 or N5), I've been able to connect to it without a hitch.  No T-Mobile software on my phone.  But, other folks have stated they've BYOD from another US carrier and had no luck with WiFi Calling.

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                  • amonra

                    Thank you! WiFi calling works fine on my iPhone, and they don’t make branded phones. This case, although I really want to switch to an S9, is proving to be unnecessarily difficult.

                    Of course they each blame each other - Samsung says T-Mobile has to enable it, T-Mobile says Samsung didn’t put the software on the phone.

                    Other variations I heard from different Samsing reps:

                    - the unlocked phone doesn’t have the hardware

                    - each carrier has a different requrement and they can’t program all

                    - it should work once the SIM card is in

                    i find it disturbing that they can’t even land on the same answer (ideally the true answer).

                    Apple obviously has figured out how to have this feature in the software independent of carrier, so we have proof that it can be done.

                      • smplyunprdctble

                        It's a problem when you have a device that is carrier branded.  Most people who want a device will purchase it from the carrier, so they KNOW that works.  Some of the configuration differences between carriers is where the problem lies.  If ATT wants XYZ turned on, but Sprint wants XYZ turned off (for whatever reason), this may not be documented to support folks (some could be complete secrets for whatever reason... like the fact Verizon and ATT had some devices previously crippled if put on another network because some settings were hardcoded in the OS instead of pulled from the SIM).


                        Apple controls everything from the hardware to the OS.  They do have "Carrier Updates" which contain certain things that are enabled / disabled based on a carrier.  Google does some of this with their Nexus & Pixel devices.  They're able to do this because they only have to guarantee industry standards and certain compatibilities.  They don't have to worry about things like Samsung TouchWiz or HTC Sense user interfaces, just the basic one they build.  They don't have to worry about any customizations the carrier wants.


                        In my opinion, unlocked and 'universal' are the best way to go, and should be the way the phone industry should work here (it's how it works through most of the rest of the world).  But, folks have purchased their phones from their provider for so long and providers still want control over the experience, so it makes it difficult.

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                      • amonra

                        On the third try, I think I figured out the WiFi calling issue on unlocked devices (Galaxy S9).  The key is to have the T-Mobile SIM card in the device before starting the setup for the first time. Doing this, the first popup I got said that the device will be updated with carrier specific settings. Then i went through the setup, and WiFi calling was there in the Phone app -> settings.

                        On another device I went through the setup first and then popped in the Tmobile sim, and the same window about carrier settings never presented itself.

                  • stillnnotmuch

                    Picking up on amonra's interesting post from August 6th, I just want to check if anyone has tried this trick mentioned in the post and worked for them.  I bought a dual sim S9+ international model (with exynos chip) several months ago and like everyone said, wifi calling option is not available.  I sold that phone but before trying a second time and buying another one again, I want to confirm that this really is the way to access T-mo's wifi calling. 


                    And does anyone know whether it  matters whether the phone is first turned on in the US or can this be done abroad?


                    I'm just tired of having to carry two phones with me all the time when working outside the US.  Any help would be appreciated.  Thanks.

                    • 6787705384

                      I don't think this will help but....

                      I bought a G960U1 from Samsung. Inserted the t-mobile sim from my older phone and started it up. After configuration, all is well. All network settings, including wifi calling) worked with zero problems.

                      It would appear that the exynos models all seem to have a problem with wifi calling.

                      I am guessing that the US models with the 845 chip need to insert the sim and then do a factory reset. As I said, only a guess.