No matter where you are, you could be upstairs changing for bedtime or just came out from shower wrapped in a towel or other side of the World, you can see from your convenience who is at the door. All you need is your Smartphone to be in the Cellular or Wi-Fi Network coverage area.
Other benefit is, you can remotely unlock your Electronic door lock. Also your iOS® or Android® APP doesn’t need to be running constantly or your smartphone doesn’t have to be wake. Your phone can go to sleep mode to save precise energy but you won’t miss your doorbell ring.