I was going to say the weird phone thing you mentioned sounds like this, but I thought they said it had to be a toll free number. So, training an AI must be it.
It's an episode of the podcast "Reply All", describing a scam that sounds very similar. Someone calls toll free numbers and tries to keep them on the line as long as possible, by being weird and appealing to curiosity, and there's some way they get money through the toll free system.
Could be they use regular numbers to train their AI or recordings to make the calls longer.