Last year, Christie's auctioned off the world's oldest telephone book. It's from 1878 and features both a residential directory and a "yellow pages." It's only 40 pages and doesn't contain a single telephone number, just the names of those who have service. IEEE Spectrum has a fun little video about the 1878 New Haven Telephone Directory.
David Pescovitz is Boing Boing's co-editor/managing partner. He's also a research director at Institute for the Future. On Instagram, he's @pesco.