Trigger event when Facetime calls..

Hi,
first of all: as you might derive from this post, I am really new to apple script.
However, I was wondering if it is somehow possible to use a FaceTime call as a trigger for e.g. muting Sonos…

I found a script that works on system events, but its not automatically checking in the background, at least its not working in my case.
The Sonos part for me is quite easy, because I am running a node-sones-http-api on an rpi, thus I only need to open the correct url to get the mute part working…

could someone shed some light to this issue?

thank you very much!

joystick