Contact Lists are fax number lists, which you can use to send a fax with, rather than having to send the fax, or faxes, to each number individually. Each Contact List may contain up to 20,000 recipients. Your users can manage their Contact Lists through the Upland InterFAX UI, where they can add/remove Contact Lists and add/remove recipients to those Contact Lists.
A nice feature of Contact Lists is that they can be shared among users within an account.
Once you wish to send a fax to a Contact List, use the POST /outbound/batches operation.
Currently, Contact Lists can not be managed through the API. The API only allows retrieval of your list of Contact Lists, with the get addressbooks list operation: