Phone spawning is not chance based but happens after an action. Don't ask me that. I'm not revealing secrets or giving too much hints.
Does it have to do with the tennis app on Ms. Yamadas phone? I only ask not for a hint, but if it does mine is bugged as I can't do anything in the app. I assumed the apps feature just isn't in the game yet, but wanted to make sure.
It doesn't serve a purpose until a major questline is added.
