How to active VOX function of H777S?

What is VOX function?How to use it?Let me introduce it to you.When using your walkie talkies,turn on this function,you don’t need press PTT button when transmiting. When VOX is on your working channel,speak to the microphone directly,it will transmit automatically.It looks like this function is very convenience,So how to operate is?Let’s learn it together. Firstly,please…