Hi. It took quite a while, but I finally got the opener working with the Tegui 374794.
To clarify: only the function to open the door using the mobile phone works. The ring-to-open and other features were not of interest to me (and I haven’t tested them).
Before running any tests, disconnect the bus by removing one of the wires.
The first thing I did was use a multimeter to find which points on the door-opening button (P3 in my case) were not connected. Then I tried bridging different unconnected points until the intercom opened the door. In my case, it turned out to be the two points on the right (top and bottom).
Next, the opener needs to be reconfigured. When it asks you to choose between “intercom” or “other door,” select “other door.” This makes the opener work basically as a relay, just acting as a bridge. Once configured, you need to identify which two wires connect the circuit when you press “open door” from the mobile. In my case, these were the blue and purple wires.
After soldering the wires to the pins, it started working “partially.” While the intercom handset was off the hook, I could open the door using both the opener and the intercom button. However, when the handset was on the hook, using the opener caused the bus to become “busy,” and neither the opener nor the physical buttons on the intercom would respond.
It seemed that a signal was being sent “backwards,” blocking the bus after opening with the opener. So I had to add a diode as shown in the photo (I just used the only one I had at home, nothing specific).
Once the wires were soldered to the pin and diode, and the diode to the other pin, it worked perfectly. It doesn’t matter which wire goes to which pin, since it just closes the circuit.
Hope this helps someone!