Enable volte on s7 edge

[Prdp1]

Hi am using s7 edge, Model number : SM-G935FD.

Unfortunately there is no option to enable VOLTE. Can anyone help me to enable it.

Note : 4G LTE works well. Am in India

[keyinternational]

7gb

[Lathasagar]

how do I enable VoLTE on s7 edge