I had purchased S8 unlocked version from Curry's in the UK coz I travel a lot and have to change SIM according to the country. To my disappointment I am unable to find VOLTE option in the settings. I believe this is a world phone and with being a flagship model this should have been enabled. Lower models do support but Samsung S Galaxy line has this issue.
How do I get VOLTE to work? Should I wait for Samsung to push a update. ?
You should have the VoLTE option in your settings buddy, to find it go to Settings> Connections> Mobile networks and you should see the option to enable VoLTE calls.
Have a look to change your network from "Global" to "CDMA\LTE" in your settings, go to Settings>Connections>Mobile networks>Network mode and change it and then go back in and see if the VoLTE option is there.