Brother MFC-8820DN - Manual (Page 319)

18 - 20 USING YOUR MFC WITH A MACINTOSH ®
When you choose work fax or home fax from the Stored Fax
Numbers pull-down list, only the fax number stored in the
Mac OS
® X Address Book for the selected category will be
used. If the fax number is stored in only one of the Mac OS ® X
Address Book categories, the number will be retrieved no matter
which category you have selected (work or home).