We have moved our kitchen down to the basement temporarily while we remodel the upstairs kitchen. As such, I wanted a doorbell camera, but not one that connected to a service like Ring or Amazon.
After much searching, I found one called the Akuvox E12W. It looked like it had the features I wanted (POE, simple rtsp stream to connect to ZM, Voip calling to act as an intercom), so I took a gamble and found a used one on ebay for around $80.00.
Setup was straightforward. The camera was immediately recognized by ZM and has worked with no issues. I use Voip.ms for my phone services, and the camera's web-interface was intuitive enough to easily connect to Voip.mss. If I were running my own PBX it would probably work just as well.
I have the doorbell part of the camera set to ring the extension for my phone in the basement. I can answer the phone and speak to whoever is at the door over the camera's intercom, or just use it as a doorbell-alert while I dash upstairs.
Camera quality is 1080p. It also has a low-res sub-stream. The model that I have (E12W) has wifi, but I prefer to have all my cams hard-wired.

