The CellNock® is the ORIGINAL Smart Doorbell Peep Hole and easily replaces your old doorbell or install it as a new one. The CellNock® D adds safety, privacy, and piece of mind to any home! You can even add CellNock® D at an entry wall, or your outside gate. Once installed you can receive alerts on your smart device when a visitor arrives and they press the call button. See and talk to visitors but can’t see you, or just monitor your visitor with the video camera. Accept or reject the calls from your smart phone or tablet. You do not need to be home to receive alerts or communicate with visitors, because you can just use your mobile device (internet connection required). The CellNock® D Smart Doorbell Peep Hole includes a wireless indoor doorbell chime. For use with an Android or iOS phone or tablet.