Hik vision intercom no cloud

I use a Hikvision DS-KD8003-IME1(B) video doorbell in a LAN network. I have 2 DS-KH6320-WTE1/EU indoor units in my house.
Everything works properly. The doorbell rings on the indoor units, I can receive calls and I can unlock the door.
I wanted to install a video doorbell on Android in hik connect (I always want to use everything only in the LAN outside the cloud).
I added the video doorbell to hik connect but I only see the stream from the video doorbell camera there (no unlocking and no calls).
Hik connect sees the video doorbell as a regular IP camera.
I was looking for information on how to do it outside the cloud and one of the few options was to use home assistant.

I apologize, but I have never used HA, because I do not have any device that HA would use.

Here on the discussion forum I found a topic about a video doorbell that works via HA, but the topic was extremely extensive (more than 2500 posts).

I want to ask if it would be possible for HA to serve as a server (maybe SIP) between the video doorbell and the android application.

The application does not have to be hik connect. It can be anything that works in the LAN.
The important thing is that the phone rings (if someone rings at the door). So that I can open the door via the application. So that I can make a call.

I have a small proxmox server at home, where I can install HA

thank you

do you need HA to be the SIP server, another SIP client or simply replace sip and completly and enable the 2way between doorbell and any client running HA web app or app?

SIP server

There are many addons for makeing HA a SIP client

Go2RTC with webrtc allow 2way audio conversation between doorbell and HA(or basically any device running HA web/app)