I don't know what to say, your demo is really bad. I cannot understand what the person was speaking after you altered the sound, this approach doesn't make sense to me.

one can just not add the ai to the call, yea?

the major call providers have settings one can use as well

Transcription can happen from audio on the system channel without a bot in the call, so if the remote user can hear it, a model can convert it to text.

The noises confuse the ASR models, I presume.

Someone could still record audio and manually transcribe it or take notes with a pen and pencil... just sayin'. Some of this just comes down to having to trust the other party.

I do take some issue with my voice almost certainly being used to train models when using certain services.