If the other carrier SIM inserted into device and if it support VoLTE by default, the VoLTE button will be visible for user to enable/disable.
Else, will require to raise through Custom Product Request (CPR) to enable the VoLTE option.
Enabling the VoLTE currently is still a manual setting. StageNow currently yet to have control on VoLTE setting, thus we need to set it one by one on the device.