There is an attempt to get Volte working on samsung using open source ims implementation
https://www.reddit.com/r/Android/comments/17u5h8u/a_volte_call_with_an_opensource_android_ims_stack/
https://xdaforums.com/t/research-wip-possible-volte-enablement-for-samsung-devices-on-aosp-based-roms.4664947/
That would be excellent news!