I work for Flywheel, an Uber competitor. We do not expose driver or passenger phone numbers to either party at all (the exact mechanism is a little different than what you propose, but the effect is the same). Driver can call passenger and passenger can call driver and neither will ever see the other person's actual number.
Good for you. Since you're doing this, and according to yid, Uber is also doing something similar, I'm even more surprised that Gett is not only exposing real phone #'s, but doing so without even requiring a phone call to be placed.
