Phone numbers remain private until a booking is confirmed.
Once a rental request has been made and accepted by the owner, the phone numbers will automatically be added to the booking summary, if they were properly added to your profile information. This way, you can easily contact each other to arrange the pick up / delivery and in case of an issue.
We recommend that you add your phone number to your account as soon as it is created. This information will not be visible to people visiting your profile page.