From: Encyclopedia of Chicago. This entry is part of the Encyclopedia's Dictionary of Leading Chicago Businesses (1820-2000) that was prepared by Mark R. Wilson, with additional contributions from Steven R. Porter and Janice L. Reiff.
AT&T's official history web site. Of special interest is the History of the AT&T Network section, giving a brief history of the Bell System's network switching, transmission and management technologies.
Telephony-related web pages
Information and links on telephone central offices, past and present
Decades before fiber-optic cables became the backbone of long-distance telephony, buried lead-sheathed clusters of coaxial cables and closely-spaced repeaters provided the nuclear-blast-resistant communications service demanded for national security. Mark Foster's well-organized web site offers detailed information about this little-known network.