To flatten User Phone numbers in a List, first you will need to have a Phone Object for each phone type you are looking to have in your List. For example if you are looking for Home, Business, Wireless then you would need 3 User Phone Objects tied to that User.
To Flatten the List with Phone Numbers (so each user only displays in one Row with all 3 phone numbers) Object Filters will need to be added.
For example, if you have User Phone, User Phone  and User Phone  Attached to User Base, then in the Object Filters you will have the following Filters:
User Phone. Phone Type any of Home User Phone. Phone Type any of Wireless User Phone. Phone Type any of Business/College