Not at home? Not able to open the door right now? Let the persons outside either get in direct touch with you or leave a message.
By taking advantage of NFC (Near Field Communication), QR codes (Quick Response codes) and the fact that everyone carries around their mobile device, you can now answer the door even when you're not at home or are unable to come to the door. This is the doorbell of the future.
Go to http://doorbl.com and "print" your doorbell.
The person outside either touches your NFC tag or scans the QR code on your front door and leaves his/her phone number. You'll be instantly notified and you can choose to call back.