Retrofitting an intercom system

Hello,

we now do need an intercom system for our house after all. We thought we could manage at least a year without one, but now it is becoming more urgent.

The range of options is huge, I can hardly keep track.

The following starting situation exists.
There is a doorbell button next to the door at the mailbox. There is the bell (the "gong") inside. And there is a doorbell transformer in the distribution box supplying 12 volts (I measured it myself).
Unfortunately, I cannot provide any information about the circuit, but I think it is the very simple doorbell circuit.
Additionally, there are three light switches, one of which is directly next to the doorbell button outside, another inside in the hallway, and another somewhat further away outside on the house wall. All light switches operate two outdoor lights, presumably via a two-way switching circuit.

There is no door opener.

And that is basically it.

Now I would like to keep the option open (because I am thinking about the future) to retrofit a "better" system.
For now, it should be something simple.
It is sufficient to have speaker/microphone, doorbell button, and light switch at the outdoor station. I would then like to install the intercom system inside in the dining room.

We do not need a door opener at the moment but would like to prepare for it in case we want to retrofit it later.

At the place where the outdoor station is to be installed, it is probably no problem to lay a power cable.
But at the place in the dining room, I have no power, and it will not be easy to pull a power cable there (despite timber frame construction).

Also, I wonder how it is possible to combine the outdoor station with the outdoor light switches (since I do not know how the light switch can be integrated into the outdoor station).

Can you help me out with what would be best to do?

Kind regards,
xola

search in this forum, at least from me there is already a thread where I compare different providers (especially in terms of price).

The ones I chose were
BuschJäger, GIRA, Ritto, Siedle.

The manufacturers themselves also provide good information by phone, e.g. regarding your question whether you can switch the outdoor lighting.
In general, this is possible, they usually offer a light button that activates an outdoor lamp.

As an alternative to the intercom system, you can also connect the outdoor station to the home FritzBox and the home DECT phones will be called.
Mobile devices also work.

It is probably not possible to get a fixed indoor station without power.
If flush-mounted cables do not work, then consider running cables behind the baseboard or in small channels under the ceiling.
Or check if there is a 5-wire cable somewhere, of which only three wires are needed.
This way, the indoor station could possibly be supplied as well. Here I definitely recommend the expertise of an electrician so that it does not become botched construction.