There are two ways to keep your number anonymous:
1. Use DirectChat
DirectChat allows you to conduct Phone Chat services without the need to work with bookings on the site. This also keeps your number from being displayed or provided to anyone as you go through the system instead of having to directly call, or be called by, a client.
For more information, please see this article.
2. You call customers
By not entering your number in the Phone Chat Number field here, clients submitting booking requests will have to provide their number for you to call them, instead of them calling you. You can of course set your number to be withheld so as to maintain your privacy.