Turn on-off VoLTE or 4G HD Voice for True SMART 4G MAX Series
- On Home screen, select [Settings]
- Select [More]
- And then [Cellular networks]
- At 4G LTE improved mode, button on the right is grey (turn off), tap this button
- Button will turn green that means it's already turned on, wait a moment for network data improvement
- Once it's ready, VOLTE sign will appear at the top center