This service is used to get the list of the available fax numbers.
Fax number aging is supported by returning inactive numbers in the list along with the available numbers. An "inactive" number is one that was assigned to a user in the past, is not currently assigned to any user, and which has not been unassigned long enough to be selected by DNIS selection methods that specify partial criteria. The purpose of this is to prevent a number from being assigned to a new user too quickly, which could result in faxes intended for the previous assignee being received inappropriately by a different person. An inactive number can still be assigned to a user by specifying it explicitly.