Activate Door Pass app on your smartphone and you will receive (via email) a unique Door Id, printed both in numeric and QR CODE forms.
Print this code in any desiderd form or size and stick it beside you traditional door bell, that's it !
When a visitor wish to 'ring' your house and you are not there, he/she can do it using any smartphone equipped with an internet connection and a standard browser. He/She DO NOT need to install anything on the smartphone.
If, as is ever more frequent, visitor have installed ANY QR READER, it is sufficient to scan the QR code to bring up, if you accept it, a conversation with you.
please note that visitor WILL NOT have access to ANY of your personal information, and that conversation is done via text chat.