Yup - the manual is not all that clear on this - used to be simpler before the voice prompt menus. From the manual with some tweaks by me... To enter into voice configuration menu, press and hold the Jog Dial for 12 seconds until the LED shows solid blue and you hear high tone double beeps. You will also hear a voice prompt saying Configuration menu. Rotate the Jog Dial clockwise or counter-clockwise to navigate between the menus. You will hear voice prompts for each menu items, until you hear "VOX intercom" You can enable VOX by tapping the Phone Button, or disable VOX by tapping the Jog Dial. If any button is not pressed within 10 seconds, the SMH10 will exit the configuration and goes back to stand-by. If you want to exit the configuration immediately, rotate the Jog Dial until you hear a voice prompt, Exit configuration, and tap the Phone Button. Hope that helps.