Voice command to switch channels

When using voice command on roku remote while on live tv it says channel not available. Is it supposed to work with ota live tv? I have tablo 4th gen ota receiver and antenna and a roku ultra

I don’t think the Tablo app currently has voice support. Trying to call a TV channel on a Roku would probably only work on a Roku TV with a TV tuner, not a standalone Roku device.