AE Director System from the 1926 edition of "Machine Switching, Volume 3" by International Textbook Company of Scranton, PA. Copy provided by Alan David.

Editor's Note by Chris Mattingly.

North Electric NX-2A Crossbar Switch by Chris Mattingly.

A Snapshot of the Bell System, 1977 (Trends in Switching Technology).

From the September 2000 Switcher's Quarterly: The 6A Key System - Part III by Joel Eves. Part of a series detailing the KTUs found in the 6A key system.

From the October 1998 Switcher's Quarterly: Direct Inward Dialing by Bruce Crawford. The independents provided it for years. See why Bell took so long to catch up.

From the April 2003 Switcher's Quarterly: The Day I Turned Off the Main Breaker by Keith Hlavacs. Find out why anyone would want to turn off the main breaker in a CO and still expect to keep their job.