The problems were how to make the directory update automatically when the data source was sorted, and how to prevent #REF! errors when rows were deleted from the data source. I created this template to answer a question posed to me by Jonathan Weinraub about how to make a sortable 2-column phone directory.
Creative Ways to Use Contact Lists Create a Running Balance in Excel that Allows you to Insert, Delete, and Move Rows INDEX-MATCH lookup formula How to Create a Sortable 2-Column List in Excel