· How to pair and set the ringtone? 1.Select one your favorite ringtone by pressing the Up/Down Control button; 2.Long Press the Volume Button for 5s until you hear 'ding' with blue led light flashes; 3.Trigger the transmitter to send a signal, then you will hear the ringtone.

· Why the internal receiver only flashes the light without any sound? The mute mode is ON, please push the volume button to make a sound, there are 5 volume levels to choose from.

· How to set different music for my front and back doors? Pair the front door transmitter with the first music separately, and then pair the rear door transmitter with the second music separately.You can hear two transmitters triggering two tones, and you will know which door has a visitor

· How to Change the Battery? 1.Use the provided screwdriver to pry open the cover; 2.Take out the battery and exchange a new battery; 3.Put the cover in its original position; 4. Push the button and test if the blue light will come on.