Monday January 25th, 2021
I absolutely love numbers! It’s one of the things that draws me to an interest in mathematics. But one of the nonmathematical uses of numbers that brings me some level of delight is in telephony, more specifically, area codes! When I was quite young, it used to be that for local calls, you would only need to remember/write down seven digits! But twenty years ago, ten digit calling even for local calls ended up becoming mandatory (read a little about how that affected Ontario here). I remember being given a ruler in elementary school with a hologram of a cartoon fishbowl to introduce us wee ones to this concept. Coincidentally, in the same year, rapper Chris “Ludacris” Bridges (who is the handsome fellow who is figured in this essay’s featured image), would release one of his best known songs, “Area Codes”, all about “[having] hoes in different area codes”. Naturally, someone who is also rather fond of area codes, maps, both, or at the veeeeeeeeery least the song, felt inclined to plot this out on a map.
Very often, when I am presented with a three digit number (besides things like “100” which I know just aren’t), one of my first impulses is to see if it’s in use as an area code anywhere in Canada and the US. Often, I wonder about proximity of numbers vs proximity of locales where those numbers are used. Here are some examples: 901 is the area code for Memphis, Tennessee, in the southern United States where it covers the smallest area of any in that state (though it used to cover all of the Volunteer State), but 902 is the one used for most of Nova Scotia and New Brunswick in the eastern part of Canada in the Maritimes where it is one of (to date) one of only three area codes used across provincial boundaries. Of course Canada has a much lower population than the United States, and it would be fairly confusing if these two places were closer. Toronto, Ontario (near Lake Ontario) and some of the area near it used to primarily make use of a 416 area code, and 415 is the original one for San Francisco, most of Marin County and a small portion of San Mateo County, all by the Pacific Ocean. Again, these are not especially close to one another, geographically. There are places in the Canadian part of the Golden Horseshoe such as Hamilton, Ontario and part of the Greater Toronto Area covered by 905, but then just west of there, a large amount of the province use 705 numbers! Montreal and Toronto are not very close on a map, but they are the second and first largest cities in the country, people often travel from one to the other and back frequently, and two of their recent area codes are very similar: 438 and 437 respectively. And Buffalo, New York, and Toronto, Ontario are practically across Lake Ontario from each other.
There were originally 86 of these North American Numbering Plan area codes, according to Wikipedia (I recommend reading the article), and each one of these had either a “1” or a “0” as the middle digit, which referred to the kind of Numbering Plan Area or NPA code it was with respects to the bounds it covered. Originally it was determined that the first digit of an area code would have to be a digit from 2 to 9 so as to distinguish the phone number from central office codes. Beyond that, each area code would have 1 as the middle digit if the province or state was divided and 0 if wasn’t. That didn’t last long, only until the early 1950s. The inclusion of different area codes in calling great distances was not widely implemented until sometime in the 1960s. The first phone call placed by a customer, however, to use area codes in calling another area which had a different code was a call to Alameda, California from Englewood, New Jersey. Until as late as 1995, all assigned NPAs had 0 or 1 as their middle digit. Not every country in North America is included in the NANP and some former members have had their NPAs changed. It truly delights me as someone who lives in the Golden Horseshoe (and with an interest in telephony) to find out that the not-far-from home 905 was once Mexico City!
Here is the map of the original mapping scheme of the NANP:
Now, originally, these codes were sparsely enough that it made sense refer to where you were from with a reference to the number of your area code like in the Ludacris song, and it is still done today to some extent. Check out DJ Neptune 973 for instance; it would be clear from the sounds of Jersey club alone that he hails from the Garden State, but he’d like to remind you every chance he gets. But what happens when a city is split into multiple numbers? Beloved cartoon The Simpsons did an episode about this, their 250th episode, Season 12 Episode 2: A Tale of Two Springfields, to be exact or or for those of you who are into this kind of thing, the production code was “BABF20”. It featured a cameo of legendary rock band The Who and was about the richer part of town and poorer part of town being divided by the implementation of a new area code which only the poorer section has to adopt. Wikipedia has a list of some future area codes you may be interested in. Check it out over here.
The system used in the United Kingdom is simply bonkers to my unaccustomed mind and I can’t write anything all that intelligible about it. To use a fairly English expression, I can’t make heads or tails of it. Check out the Wikipedia article here and baffle yourself. I bet that even if you’re from there, it may be incredibly daunting, unless that’s your line of work, of course. And other countries have other systems. France has abolished area codes which sounds very “progressive and European”, I say tongue 100% in cheek, but the truth is, they’ve been through a small handful of different approaches, seemingly changing every 15-20 years or so since the 1980s. There are aspects of some of the different methods I can somewhat follow, but truth be told, it’s more than a little bit hard to do so for long (as I write this), with all this business of dialing trunk codes, subscriber numbers, access codes, and so on.
Of course, despite their restrictions, NANP area codes, are of course… numbers. Here are some area codes shared with some tangentially related bits of trivia. Not included of course are mathematical properties of these for now, since for many three digit numbers, there are some interesting things along those lines that may not interest everyone but I will include one of these as a link and teaser of sorts another post of mine
404 – This area code for Atlanta, GA is also a “Page Not Found” error that you’ve likely encountered before browsing on the internet
713 – The NPA for Houston, TX is the number of letters on a halachic mezuzah scroll
201 – The area code for northern New Jersey is also part of the name of “201 Penelope” an asteroid found in the Main belt in our solar system, discovered August 7th, 1879. So if you have a daughter born August 7th, maybe Penelope would be a good name for her.
438 – One of the newer area codes for Montreal is a number that also has some significance in cricket as part of an incredible game between Australia and South Africa which has since been referenced simply as “the 438 game”
656 – This new area code for the Tampa, Florida area which you can read about here is also the amount of times Jerusalem is mentioned in the Tanakh
431 – One of the area codes for the province of Manitoba, Canada is also the distance between Earth and our current pole star, Polaris in light years.
703 – This NPA that covers much of the Northern Virginia area (including Alexandria and Fairfield) is both a triangular and a hexagonal number
956 – One of the area codes of Southern Florida including Fort Lauderdale is also the ISBN Group Identifier for books published in Bulgaria (more about ISBN and cataloging in a future entry)
Listening while writing this post included NTS Session 3 and Tri Repetae, both of which are by Autechre in 2018 and 1995 respectively as well as the following EPs by Glenn Wilson: H4, 2755, Class of76, Beta 6, Further Advances, and Killing Spree