Going by usage, buttons should be place either close to the subject where it refers to (like the close to the phonenumber) or close to a place where the thumb will be comfortable to use.
The screen I have defined, I am wondering where I should place the "call me" button. I have placed it below, I wonder if its most intuitive. Also note that this is the only screen the customer will have a chance to call the driver. Before this the confirmation is under process.

Edit :
As the app loads, the user uses all their fingers (to enter the destination). After that this screen appears as a FYI. Calling the driver is the obvious default behavior. I wonder if I should rename the GotIt to something else like, LATER. Or Thanks. This action will save the ride to booking status list.
Edit Again : This screen appears when the customer wants to know the status of the driver, ride or just talk to the driver.
