VOX stands for "Voice Operated eXchange," a feature that allows hands-free operations in supported walkie-talkies. Also known as a voice-operated switch, VOX automatically turns on the transmitter or recorder when the user speaks loud enough and off when the speaker remains silent.
Most walkie-talkies are operated through push-to-talk buttons, which are used to temporarily switch the devices to transmit mode from reception mode. With built-in VOX capability, on the other hand, users can open the walkie-talkie channel and communicate easily through voice activation. Certain walkie-talkie models also have the ability to attach audio accessories, such as headsets, external speakers and microphones, to supplement the VOX capability.