PoE Doorbell to SIP Video Phone

[user_664640953340025_664640953340025]

I was a software developer in a former life and I'd like to create some software (running on a small network connected embedded Linux server similar to an inexpensive raspberry pi) which integrates the PoE Doorbell camera with industry standard SIP video calls but also includes a relay that can momentarily energize a electric door strike to unlock the door.

Basically my plan is to receive the button press with ONVIF and then take the RTSP video stream from the camera and use that to make an actual SIP call to a Video Phone and once the call is answered we would relay the video and audio from the camera to and from the SIP telephone, in particular relaying the audio from the person answering the call back to the Doorbell Camera, in effect creating a real-time video call. Similarly what I would create would also register as a SIP extension so one could call the assigned extension number from a phone (which would auto answer) and make a video call connection to view the camera on demand (and useful for instance if you are expecting someone). So in effect this small drop in network connected box would turn the PoE Doorbell into a full feature (as much as is possible) video phone. Once such a video/audio call is established, entering a vertical service code on the phone dial pad could momentarily energize a door strike to unlock the door. Obviously, a SIP video phone wouldn't be required (just nice to have), could still do the same thing without video, just using audio in both directions to a less capable or really any phone.

All I would be doing is translating and relaying the traffic and while most of this functionality could certainly be built into the firmware itself on the camera, the device is proprietary so it's not like Reolink publishes their schematics and source code or has enough flash memory to hold such larger firmware image with all this additional added functionality or even that the cameras embedded processor has the memory and CPU resources to do all this.

I have no problem figuring out how to make a video SIP call to the phone but the requirements of communicating with the camera (sending and receiving audio) don't seem to be documented?
Is there any documentation anywhere that anyone knows of that could give me the details? I suppose I can get the details in a round about way by capturing the network traffic when the camera is communicating with the Reolink app but I'm trying to avoid having to do this kind of reverse engineering exercise.

Any insight appreciated.

[joseph_1979]

@user_664640953340025_664640953340025 I have asked for SIP calling on the doorbell camera for quite some time to close the gap with their competitors who already provide. Maybe they can provide the SIP client and then we register with a VOIP service provider.

[user_664640953340025_664640953340025]

@joseph_1979 Yes, well as nice as that may be, I won't be holding my breath for all that capability to be added to the firmware anytime soon. In fact it's likely not possible without a new hardware version with the processing power and resources to support this.

My "plan" is to create a simple, drop-in network device that connects to the camera and is also capable of placing SIP audio (and video) calls and will act as a bridge between the camera's already existing firmware features and functionally and standard SIP telephone networks (and by extension any telephone).

While SIP protocols are well documented and even well understood by me due to extensive experience in this area, how to effectively communicate with the camera is less clear (at least to me). Even when I go down the ONVIF protocol rabbit hole, there is no clear definition of which features are actually implemented in the Reolink PoE Doorbell camera or the minor implementation variances specific to this model and not many open source software examples to learn from.