I doubt any of the people collecting phone numbers as an identifier are actually making any calls. They use it as the ID to link all of your data collected by them by anyone else that buys that data to other data they've bought from other suppliers.

In fact, if that is a legit number, then all I'm doing is increasing their rewards points or whatever. Sure, maybe messing with their recommendations like when you share your Spotify account, but that's a whole lot of meh from me on that.