Here are some sources for old telephone books, which may give you contact information for relatives who are now unlisted.
One way to get around unpublished phone numbers is to go through a town’s old telephone books. If someone’s lived in the same town for a while, you might locate a listing prior to his or her unpublished-number status. Here are some resources for tracking down telephone directories:
• The Library of Congress:
For information on the collection of directories at the Library of Congress, check out Telephone and City Directories in the Library of Congress: Current Directories
and Reverse Directories in the Library of Congress