A variety of ringtones-free switching, 25-polyphonic ringtones can be freely, elegantly and beautifully switched.The ringtone and volume can be adjusted to meet your original needs.You no longer have to worry about being unable to hear the sound or hear the sound too loud. When the visitor rings the bell, the monitor activates and displays the image outside. Press the answer key to make an external call, and then press the answer key to turn off the phone. If no button is pressed or no one answers after the call, the display turns off automatically after 60 seconds. One camera can be used with 6 indoor monitors.One monitor can be used with 2 cameras.The camera can talk to the display.The monitor can also talk to one of the monitors. (If you need more cameras or monitors, please contact us.) The outdoor camera has built-in 4-white LED lighting.With this feature, you can see the outside no matter day or night, making your home safer. Sensing White Light Effect, Night Vision Effect, No Night Vision Effect (Color Picture, Best Near Vision Effect) Waterproof and dustproof, the outdoor camera is equipped with a weather resistant lid, so it can be used outdoors in very bad weather. Unlock with indoor monitor (screen) The video intercom system can be used in combination with an electric lock.You can use the room monitor to open the door.There is no need to open the door for your visitors.very convenient! (Note: the electric lock is not included in the package and must be purchased separately) Package includes: 1° doorbell