Well the ability is there, through the “Customized script” option inside the camera:
Here is an example of the syntax see page 37-39:
http://download.vivotek.com/downloadfile/downloads/usersmanuals/ip21x2manual_en.pdf
That said I just use it for recording video\audio. It does have a two way audio if you pull up the web interface inside internet explorer and there is an app (android\apple) that probably works with it though I haven’t tried the app.
https://www.vivotek.com/iviewer/#views:view=jplist-grid-view
I use it with blueiris (a nice inexpensive dvr that is compatable with almost all cameras) which I launch via shortcut inside openhab, but there is a nice writeup on full integration here:
The camera also has the ability to save recorded video\pictures to a network share or ftp server, so you can set it up without any additional software. There is quite alot of cool motion detection/event capability baked right into the camera.
I have a feeling to get the doorbell button working your going to need to get your hands dirty with the custom script using the examples in the manual and the variables listed under “System” => “Parameters” Here is a screenshot of the area you’d be interested in.
I have a large glass window on my front door so there was little motivation to get that part working.
The first steps are to pair the doorbell to your wifi… here is a good how to to get into the doorbell if your comfortable with how WPS works:
Let me know if you have any other questions, or get stuck. Most of it is self explanatory once you get into the web interface of the camera. If you decide to get adventurous and play with the scripts post how far you get so others can maybe add to it. I havent gone that far but hopefully the links here helps get you to the right place.