Once upon a time, telephone customers were assigned alphanumeric telephone numbers. For example, the numbers were such as FOundation 8-3556 (now 368-2556), MOnument 2-2491 (now 662-2491) or NEvins 8-3886 (now 638-3886). The letters and first digit designated a certain geographic area and were referred to as exchanges. Numbers beginning with FOundation were in the vicinity of Lenox Avenue and 135th Street in Manhattan. A large segment of today’s population has no idea of the concept of alphanumeric telephone numbers.
“You could learn about a fella by knowing his exchange. A MOnument fella was up near 100th Street and West End Avenue. You could picture him coming downtown on the IRT, strolling first to 96th and Broadway for the newspapers, passing the Riviera and Riverside movie theaters (both gone). The ATwater girl was an East Side girl, a taxi-hailing girl, on her way to her job at Benton and Bowles. A CIrcle fella was a midtown fella, entering his CIrcle-7 Carnegie-area office with a sandwich from the Stage Deli. And what about a SPring-7 girl, twirling the ends of her long brown hair as she lay on her bed talking to you on the phone? A Greenwich Village girl. A 777 girl is nothing. She is invisible. She is without irony, seldom listens to music.” — Jonathan Schwartz, New York Magazine, December 21 – 28, 1987, as reproduced in Once Upon a Telephone: An Illustrated Social History, (1994) Stern and Gwathmey, New York. Harcourt Brace and Company
This ad containing a DE exchange can be found on a Midwood apartment building just off the Q train at Avenue M. To my surprise the DE exchange did not stand for Delaware; instead it stood for DEwey.