In order for songs to be covered under the CCLI Copyright License agreement, the song must be contracted with CCLI®. When the copyright ownership is unknown, it is not possible for the song to be covered by CCLI.
If a song is in the public domain, it would be free to duplicate without permission. Typically, songs that were written over 100 years ago would be in the public domain. Here is another tip: If the song book is published before 1989, any song contained in that book without a copyright notice would be considered as public domain.