Set default privacy for new users' contact details
You can choose which contact details are private by default when you add new users, so people don't have to remember to lock them down themselves.
Who can do this: anyone with the Modify Site Settings permission (Administrators have it).
Set the defaults
- Go to Administration > Site Administration > User Information.
- Under Default User information Privacy, check each field that should start out private: Email Addresses, Phone Numbers, Current Address, Permanent Address.
- Click Save.

The defaults apply to users you create from now on. Each person can still change them for their own details in their profile, using the lock icon beside the field.
Who sees private details
Private details show on a production's contact sheet only to people whose role includes View Contact Sheets w/ Private Information. Managers and Administrators have it. You can add it to a custom role too. See How user roles and permissions work for how roles are assigned, and Accessing your Contacts for the contact sheet itself.