Note here, I am a One Plus Add on subscriber and should have access to VoLTE, VVM, and RCS.
I've had a moto x4 since January, where in it was originally on Android 8.0, and it has updated to 8.1, and to 9.0 via OTA.
I have also tried a custom rom to determine if the device being Android One for Google Fi has caused any issues. (it shouldn't, google Fi is a MVNO of tmobile and uses tmobiles towers)
Best I can tell VoLTE, VVM (native), RCS (native) are not nor have they ever worked on my device, despite Tmobiles IMEI Check stating they should and the hardware allowing it.
- VoLTE is provisioned according to the dialers settings, however any call incoming or outgoing instantly drops my LTE signal to H+. I have HD voice, but that does not require VoLTE and can be implemented over HSPDA and EVDO
- Native VVM does not work : half the time it does not show up in the stock android 9 google dialer, and when the tab is there it gives some error as to being unable to connect, or try again, or call your voicemail to complete set up.
- RCS, Chat Enhancement worked long enough to get my password to set it up sent to me via text message, then vanished from my message (googles Messages) apps settings stating no carrier support.
Now, VVM worked on my Xperia X Compact until around October of 2018 then stopped functioning(unlocked phone, but it had stopped getting updates around late 2017, i held mine back to android6.0).
VoLTE and native VVM work on a Blackberry q10 (tmobile branded) and on a BlackBerry q20 (unlocked) are still functioning as of yesterday.
Is there anything in the works to remedy this? If all these features work on Fi, which uses T-mobile as the back-haul, there is no reason I can see they don't work on the real network. Will unbranded users ever get access to this? - I've even seen posts noting that pixel3 users may not even have native access to these features despite being sold in the brick and mortar stores
And no, using the horrid T-Mobile VVM app nor digits app is not an option : it never buzzes, fails to notify, is clunky and slow, and should not be required. With all these ads about being the "uncarrier" this is a pretty "2008 carrier" move to require junk apps to work basic functions.