On a half-duplex transceiver, the VOX function is useful for communicating without the need to press the PTT switch, allowing hands-free operation.
As soon as you start talking, the VOX function automatically activates the transmission, the more technologically refined this function is, the more it will be able to sensitize itself to the human voice and not to environmental noises, thus preventing the transmission from being activated with an unwanted audio source. In addition, the VOX function often has the adjustment of the audio sensitivity necessary to activate the transmission.