My own opinion of doorbell cameras, at least most of them, is that they're not yet ready for prime time. Too many WFi problems, most are cloud connected and that introduces lots of delay...even more than IP cameras already have, the cloud services don't seem to be reliable, firmware gets to be a real PITA, quality of the cameras seems to be a little on the questionable side in terms of being weatherproof and smudges/dirt on the inside of the dome. They use power from your doorbell and digital doorbells can be a problem while mechanicals can end up humming constantly due to the constant current through the coils of the doorbell.
Doorbird, at least I thik that's the one, is a hard wired PoE camera and seems to be better as a result. Looney tested the Dahua offering and found it, shall we say, seriously lacking. You're better off with a real PoE camera covering the door and a standard intercom, at least to me.
We'd all like that option of getting a notification on the phone and instantly looking at the live video. Keep in mind IP cameras have an inherent delay between the live action and what is displayed/analyzed, say at least a second and maybe as much as three seconds. Now, add in the time needed for a notification to be generated by a program and get to your phone from your network device, whatever it is. Next add in the load time for the app on the phone. Now add in the round trip times between your phone, your mobile provider, your cable provide and your own LAN. By the time you get the notification, open the app and respond, just a guess but 10-15 seconds or more isn't out of the realm of possibility, whoever was at the door is gone.
I know Ring shows instant response in their commercials, but those are commercials, not "real life" and, IMHO, are very misleading. Sometimes it's tough being a skeptical curmudgeon so I like to think I'm a realist.
Its still early in Hong Kong, he will answer.Im not getting any response through that email. Didnt say hes on vacation?