Default VoLTE on AT&T Note 3 with T-Mobile sim?

I use AT&T note 3 on t-mobile. 4.4.2 official AT&T kitkat rom. Rooted (couldn't get hotspot working without root)

I don't think there's a way to flash T-Mobile rom on my phone, but wonder if there's a way to get volte to work on this phone on t-mobile.

Do I need to wait until AT&T sends out volte update and will it work with T-Mobile? Is there a chance I won't be able to root\use hotspot after such update?

Can I tweak anything to make it work?

Currently, when I get a call while hotspot is on, network switches to 4G and never switches back to LTE until the hotspot is turned off... and the only way to get around this issue is to forward calls (or switch hotspot off and then back on)

I know T-Mobile is pushing out volte and people on xda say it works in my area.