Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. n telecommunications, a voice operated switch, also known as VOX or Voice Operated eXchange, is a switch that operates when sound over a certain threshold is detected. It is usually used to turn on a transmitter or recorder when someone speaks and turn it off when they stop speaking. It is used instead of a push-to-talk button on transmitters or to save storage space on recording devices. On cell phones, it is used to save battery life. On Intercom Systems that use a speaker in a room as both and speaker and a Mic will often use VOX on the main console to switch the audio direction when a conversation is going on. The circuitry usually includes a delay that leaves the circuit activated for a short time after the sound stops. This keeps the circuit from turning off during short pauses in speech.