Help with Bitron Video MV1000 installation (opener)

Hi there,

I need some help if possible for the ring detection.
I have a Bitron Video MV1000 that is not supported by Nuki Opener.
In this case i tried the generic analogue way with 50% success (please check pictures attached)
I am able to open the door connecting the ground correctly (purple and black) and the blue wire in the “Open” input of the intercom.
However I can’t detect the ring signal correctly.
The only input where I detect the ring is the same of the “Open” input but in this case when I ring my neighbors bell it will detect too.
I started to search and I read here that it may be possible to put the Nuki opener to detect the ring from the speaker. I sent attached a picture of the speaker where my bell rings so that we can check if it is possible to make that change in my Nuki and see if it works.
I have a multimeter if we need to check voltage diference on connection “P” of the diagram (instead of connecting it to speaker)

Thank you,
Pedro