Sprint HTC U11 unlocked but not working properly with T-Mobile

[Packaroo]

So I recently bought a Sprint HTC U11 off ebay, and at first it didn't work at all with my T-Mobile SIM, all it showed was a full strength signal with a capital R next to the signal bar. I called Sprint and they confirmed it's unlocked, although they said it may still be tied in some way to the original owners account, which could potentially cause problems.

I managed to get it working on LTE, by going into testing mode (*#*#4636#*#*) and setting the network to CDMA/LTE only, but with this setting I can only use Data, no Calls or Text. It is also has Sprint as the provider instead of T-Mobile, and I can't switch on VoLTE (greyed out in the Testing menu).
I tested it with some of the other settings, but anything that turns on GSM makes it glitch out, connect for only a few seconds to either T-Mobile or U.S Cellular (a provider I automatically roam on where I live), and then disconnect and refuse to reconnect to anything until I switch back to CDMA/LTE and reboot.

Is this a common problem with the Sprint version of this phone? Are there any fixes for it? The phone is currently not rooted or modified in any way, and is running Android 8.0, Software version 2.33.651.10.

Thanks for any help.

 

[Mikee4fun]

So I recently bought a Sprint HTC U11 off ebay, and at first it didn't work at all with my T-Mobile SIM, all it showed was a full strength signal with a capital R next to the signal bar. I called Sprint and they confirmed it's unlocked, although they said it may still be tied in some way to the original owners account, which could potentially cause problems.

I managed to get it working on LTE, by going into testing mode (*#*#4636#*#*) and setting the network to CDMA/LTE only, but with this setting I can only use Data, no Calls or Text. It is also has Sprint as the provider instead of T-Mobile, and I can't switch on VoLTE (greyed out in the Testing menu).
I tested it with some of the other settings, but anything that turns on GSM makes it glitch out, connect for only a few seconds to either T-Mobile or U.S Cellular (a provider I automatically roam on where I live), and then disconnect and refuse to reconnect to anything until I switch back to CDMA/LTE and reboot.

Is this a common problem with the Sprint version of this phone? Are there any fixes for it? The phone is currently not rooted or modified in any way, and is running Android 8.0, Software version 2.33.651.10.

Thanks for any help.

Do the following on the thread and everything will work.
https://forum.xda-developers.com/u11/how-to/convert-sprint-branded-u11-to-unlocked-t3664154