Custom ROM - VoLTE

Hello,

I have a G900A S5.

G900A is rooted and on lollipop 5.0 with OA1 bootloader.

I would like to know is there any custom ROM which I can flash and VoLTE can work on that with any international SIM?
Basically, G900A requires ATT SIM for VoLTE to work. But I would like to have VoLTE with different operator so please suggest which custom ROM to use if any available.


Thanks.