What you have to know is if the phone is not sold by T-Mobile, there is a good chance that you will never be able to use the WiFi-Calling, which is stupid, totally...
Anyway, what matters here is the radio frequencies. Can you have access to T-Mobile networks LTE Band ?
You can check the specs of your phone, look at the bands, and check with the bands used by T-Mobile.
Foreigners, when they travel, they connect to many different carriers network, and it works. The only thing is you might miss some bands, and then, you don't get the LTE. That's it. But the 4G, yes.
SO of course, when it's your main carrier, that you use every day, you want to be sure you get what you pay for. So chaeck the specs of your phone, and compare to the LTE bands of T-mobile. And there, you will see if it works.
Thanks, I understand it's about frequencies and from all indications the Sprint Samsung Galaxy S7 SHOULD be compatible with T-Mobile network (minus VOLTE and WIFI Calling, which as you point out are locked to only be used by devices running T-Mobile firmware). The T-Mobile and Sprint S7's are the same hardware wise with the same radios, however if a device from another carrier (even unlocked) is running another carrier's firmware then certain frequencies can be blocked. On the S7 carriers were apparently notorious for disabling/locking out radios for other carrier's LTE bands even though the device supports them. Which means while a device may technically be compatible it basically isn't without flashing T-mobile official firmware onto it. This issue went away with the S8 as then Samsung made BYOD as simple as swapping carrier SIM's into a SIM unlocked device (even carrier specific one) and it automatically adapts the software to that carrier.
So I figured entering the IMEI on this tool would tell me if it was compatible or not, but this isn't working.
I was hoping to be able to know whether current Sprint S7's will work on T-mobile BEFORE switching over only to find out they won't work so we have to either switch back to Sprint or buy all new phones. Being as our phones are only a couple years old now and new ones cost $1,000 anymore, switching isn't an option if we have to buy new phones just to use the T-mobile network. If only VOLTE and Wifi calling don't work but everything else does without having to do anything but install the T-mobile SIM (meaning they still run Sprint Firmware) then this would be perfectly fine with us.
I know that for Android phones, carriers are putting their own firmwares, which is a pain.
I am personally using iPhone, and the carrier is doing nothing. No firmware for them.
VoLTE and WiFi Calling are blocked by T-Mobile just to force you to purchase a phone through them.
As I understood, if the phone is sold by them, and you have one, it's not linked to the firmware, but the model.
Anyway, this sounds like a bad behavior from T-mobile, and so many users are so clueless about technology, and they believe what thy are told, which is 90% of the time wrong from the people working at the store.
You can try to call their hotline, and see what they say. But you are right, you rather have to verify first. Maybe take a prepaid card, and check the functionalities first. Cost a little bit of money, but at least, you know if you can switch or not.
Sorry not being more helpful
It should work fine as long as the device is SIM unlocked. It doesn't support all of the T-Mobile bands running tjth firmware but it xoes support enough tonwork fine.
This wasn't working yesterday. I checked the website again today and it does appear to be working. Not sure however just how this is any different than the BYOD mobile app as they both appear to give the same result