You know how the answering machine is? Well, it can be a video kind made for doors. If it's important concerning who the person is come to the door for whatever reason... The person can press a button and record a short video message for the householder or one living in the house they are there about. And the householder or other ppl living in the house can be there or not be there to see the video message live as it's getting recorded and/or later review the video message. Another technology is a sense video recording... You know how them doors be at stores in how they sense and then turn on so that the door slide open? Well, if a camera is made that way for whose at the door, then you'll know what person been coming around when you're not there. Hey, might catch a thief casing out your place or know if so-in-so did come by. And you can save in time on not having to rewind and watching lengths of footage not catching anything like how it is with that always on video camera recording which is B.S.ing you. Ha! How is that for technology?! A door's answering machine! and a sense feature for activating a camera for whose ever at the door! Can make them. It's just how the design goes so it's set for at a door where an inventer(s) comes in. Can be different designs by different inventors. Ha! I'll be one of the inventers originally with a product sure a market is for world wide. Can even make it so any triggerings of catchings or video messages left are easily accessable online from any location you are with a computer that's online. Then when you're on vacation (or at work on break, or etc) you can keep tabs on who all came by your place. And the door answering machine for video messages can even have your pre-recorded message play or not play upon someone pressing to leave a video message. The pre-recording message may be anything. Like: "Hey! Let me see those pearly whites if you mean good. And know, I may or may not be in right now, but that's my business. But um, just leave a short message with your name and address or phone number which I may reach you by along with any detail as to exactly what business it is you have with any of the occupiers of this household. Thank you!" And you can record their reaction to the pre-recording to see if their bitchin on the low so you can see if they are sincere. Also the sensor which trips on the camera by any person standing there, can also voice a message to let whoever it is know you got 'em on camera. Can say, "Hey you! Smile. You're on candid camera." Plus, also if the police ever come to your house and end up leaving you abused without giving their badge numbers, you'll at least have their facial descriptions as hardcore evidence against such crooked police officiers. I mean, you do know how crooked police may even wear or show a different badge number so they can get away when you come to find out the number you wrote down doesn't even exist. Tell those crookid escape folks then to eat their heart out.