Sometimes it’s just easier to message your Uber driver than try to call him or her. And that’s why Uber has started to roll out globally an in-app messaging feature to make it easier to get in touch with your driver. When you tap on the Contact button below the driver’s name you’ll see a chat window there. Your messages to the driver will be read to them, so they can continue driving safely. If they need to respond, they can just do so with one tap and a thumbs up icon will be sent to the rider. But if you still need to call the driver, there will be a phone icon on the upper right hand of the window.
Source: The Verge