Voice Operated Transmit (VOX)
VOX stands for Voice Operated Transmit.
This enables you to transmit without using the Transmit button. Your voice activated the transmit function when you speak.
This is usually a function of the radio but usually depends on having a special VOX earpiece. It works by measuring the general noise level from the MIC and causing the radio to transmit when the user speaks above a certain level.
VOX works best where noise levels are steady and predictable. (It is easily triggered by wind noise). It is much easier to set up and sue with radios that have many VOX adjustment levels, variable Mic Gain and VOX delay times.