I agree that are very different, but in the technical part, for regular users (those who make massive this products), you just have a phone number (email addres

I agree that are very different, but in the technical part, for regular users (those who make massive this products), you just have a phone number (email address) and download the WhatsApp app / login to web.whatsapp.com (download Gmail app / login to gmail.com). This let me think, what happens if you send a WhatsApp message to a phone number that is not registered on WhatsApp? Its saved till the user create an account with that number?