There are letters on my telephone dial.
This fact does not surprise you. "Of course there are letters on your telephone dial," you say. "How else could you dial 1-800-CORRECT? How else could you dial 1-900-HOT-SEX? How else could you say 'My phone number spells out PIGEONZ'?" (Ever notice how in movies they use "555-" numbers to avoid accidentally giving someone's real phone number? Don'tcha hate that?)
But the letters on the telephone dial weren't put there so people could spell out cute words with their phone numbers. The letters were included to spell out exchange names.
It seems that back in the old days of telephony, before there were dials on phones, you would pick up your telephone and give the operator the number you wanted. That number usually consisted of four or five digits, preceded by the name of an exchange, a particular region within the city or calling area. The exchanges were usually named after some feature of the local region; for instance, if you wanted to call the Pennsylvania Hotel, near Penn Station in New York City, you would ask the operator to connect you to "Pennsylvania 5000." (Later exchange names were assigned by the phone company and apparently often had nothing to do with the local region.)
Eventually, dials were added to telephones and you could dial the number you wanted directly, without operator intervention. The phone company, in its infinite wisdom, kept the exchange names around; it felt that seven digits would be too hard for most folks to remember. But how to dial the exchanges on your new dial phone? Simple—the phone company assigned letters to each number, and marked those letters right on the dial. To indicate an exchange, you abbreviate the exchange name to its first two or three letters and dial those; you could reach that hotel by dialing PENnsylvania-5000, or 736-5000. (I think you had to be in New York, though, or get an operator to connect you to New York; this was before area codes.)
Initially exchanges were abbreviated by their first three letters in many places, a system referred to as 3L-4N (three letters, four numbers). Most places switched to 2L-5N between about 1930 and about 1950. The PENnsylvania exchange became the PEnnsylvania-6 exchange; new PEnnsylvania exchanges could then be added by using a third digit other than 6. You could still, however, reach that hotel at PEnnsylvania 6-5000.
In the '50s and '60s the phone company decided that the 2L-5N system was a bust, and switched to ANC, All Number Calling, whereby an exchange number no longer bore any relation to a word. There was heavy resistance in some quarters—in the San Francisco Bay Area, for instance, the Anti-Digit-Dialing League was formed to protest. Some exchange names persisted, but by now they've all faded away.
But all is not yet lost! Thanks to Robert Crowe and the other folks at the Telephone Exchange Names Project, you can find out what your local exchange was historically, or (if your exchange number is too new to have a historical name) pick a historical exchange name to use. Then you too can be cool and retro by giving your phone number starting with an exchange name. Next time I order pizza and they ask for my phone number, I just might start out with "YOrkshire 2..."
I was originally going to focus this week on cool or amusing telephone number mnemonics, tips for finding good mnemonics for your number, and what to do about those pesky 1s and 0s in numbers. But I think I'll save that topic for another column.
Particular thanks to Jeff Vorzimmer for providing (on the TENP historical page) a concise history of the telephone exchange system.