T-Moble 920T SIM Unlocking and keeping WiFi Calling and VoLTE (Can it be done?)

Guys, I have a question for anyone that's SIM unlocked their 920T's. At the moment, my 920T is running xtresolite 2.2. It's based off a 920F firmware. As you know, this is an International version. To further complicate things, I needed to SIM unlock my phone so right now I'm using the MetroPCS COF9 baseband. Every time I switch back to a T-Mobile based ROM, my SIM unlock gets pulled and the phone is relocked back to T-Mobile (has been confirmed in multiple posts on XDA). I'd just stay with xtresolite 2.2 but I have no wifi calling or volte. I'm trying to find a rom for this phone that supports a different carrier sim as well as volte/wifi calling when I switch back to my T-Mobile sim. Is this possible?

All the ROM's I find for the 920T are either locked down T-Mobile ROM's under that development section and the general development section is mostly compatible International variants - but lacking WiFi calling or VoLTE. I'm beginning to think these two things just can't work together on the same ROM.

Thanks so much in advanced for a reply!