What Your Area Code Used to Say About Your Location

This is something of a side diversion from my Telephone Tales, just a bit of phone lore that used to be part of a “history of telephony” presentation we would give to fresh out of college developers to explain why things were the way they were.  I gave this presentation, which included the development of digital telephony, early signaling methods, ISDN, and a few other topics, quite a few times.  I always enjoyed this particular section of the presentation for no better reason that it was purely history by the time we were talking about it.

I have mentioned the North American Numbering Plan previously.  It came about in the post-war times when the phone companies, and specifically AT&T, saw a time of growth in demand coming and wanted to be able to meet it while not having to hire more operators to handle every long distance call.  The plan came together, was agreed upon, and began being implemented in earnest the early 1950s.

By the time I was born in the mid-1960s it was in place, if not completely implemented in every distant location.  As I noted previously, into the late 70s there were still rural locations where you need operator assistance to make a long distance call.

The plan was simple in its inception.  It reserved a set of numbers to act as area codes, and a secondary set to act as prefixes.  Area codes covered a specific geographical location while the prefixes indicated, within an area code, which central office, or phone switch within a big multi-switch central office, was being called.  The last four digits were open and were essentially the extension from a specific phone switch.

The original plan

So the phone at my grandmother’s house, Which was YOrkshire-7, 3664 in the immediate post war period, became 415 for the area code, while the prefix 967 put the location of the phone switch in the Mountain View/Los Altos vicinity.

There were just 152 area codes within this plan, under which there could be 640 central office locations.  That has long since changed, but it went this way into the 1990s.

Now, AT&T and its lesser rivals had to distribute area codes across the country, and when you look at the map you might not see any sort of logical pattern when compared to, say, ZIP codes… which also came into being around the same time… where the lowest numbers are the northeast of the country and the highest numbers are in Hawaii in the extreme southwest.

You look at the original map and it seems like chaos, or maybe they threw darts at a board or something.

The original area code implementation

I mean, it is not complete chaos.  You can intuit at least that they first divided the map up based on population to allow for the need for phone numbers, with each state getting at least one area code.  Wyoming gets an area code of its own despite its current population being about half of New York City’s population in 1880.

New York City though, it got its own area code.  Its population and population density drove a lot of technological change in telephony in post-war world.  The T1 line was an early solution to its population density.

New York City got the area code 212. (And there is a whole history of NYC are codes.)

Why 212?  Because of its size and density, it put a lot more strain on the phone system, not just in the city but nation wide.   A lot more long distance calls went there than… well, certainly more than Wyoming.

And in that era everything was pulse dialing.  When you spun the dial on your rotary phone you were picking how many pulses would be sent for that part of the operation, going from 1 to 10, the zero being 10 pulses.  The more pulses, the longer it took to transmit, the longer the switch waited, the more pulses it had to turn around and deliver to the next switch, and so on, cascading down the phone network.

So if everybody is calling New York, then you really want calling there to generate the minimum number of pulses, and in the dialing scheme, the area code 212 generates the least number of pulses.  So New York got 212 (5 pulses, 2+1+2=5).

With that in mind, you start to see the area code map as a judgement on network traffic.  The next two lowest numbers, 213 and 312 (6 pulses each), went to Los Angeles and Chicago respectively.  Places with a lot of traffic got lower numbers, with the middle number, which has to be a 1 or a 0, being the prime indicator.

There is some thought that goes into the more rural locations.  Being adjacent to a big city made it more likely that you would get a 1 rather than a 0.  Being outside of Chicago means you are more likely to call Chicago or get calls from Chicago, living in a suburb.  And we might not think much of Kansas as a state when it comes to size, but Kansas City was big enough to both split the state into two area codes and to grant both the coveted 1 for the middle number.

Meanwhile, Hawaii got 808, which is more pulses (26) than even Prince Edward Island in Canada and its 902 area code (21 pulses).  And Alaska got 907, also 26 pulses.  Welcome to the country new states!  Nobody is going to call you.

In addition to all of that, there was a strong desire to avoid mis-dialing, which led to the approach of adjacent area code locations having non-adjacent numbers.  It wasn’t quite to the level of no area code being next to another that started with the same number… you can see Alberta and Montana, area codes 403 and 406 (17 and 20 pulses), touching across an international border… but it came close to that at the start, though the idea quickly became untenable as the demand for phone numbers accelerated.  As noted, Silicon Valley picked up the 408 area code, carved out of the southern end of 415.  But when the East SF Bay region needed a new area code, they got 510 (16 pulses) in part because Silicon Valley was still viewed as a rural backwater while Oakland, at the core of the 510, was a major city and a nexus for commercial and government offices.

That map above is way out of date.  By the time I was born the 415 area code (10 pulses) had grown so much that what would become Silicon Valley had been segmented out and given the 408 area code (22 pulses, so not very important!), while the central valley of California had been assigned 209 (21 pulses, so Fresno was more important than San Jose).  (And there is a whole page on Wikipedia about US area codes and when they were added if this interests you.  I could sit on that page for hours.)

And, of course, what counts as an area code has change, starting with 800 numbers, or WATS lines, the toll free phone numbers that were in so many a TV ad in from the 70s forward, being sliced out of the area code plan.  Then there were 900 range numbers, probably most famously remembered for the 80s/90s 976 numbers in the US for things like the Psychic Hotline.

A company I used to work for got its start in the telephony service market by hosting the Psychic Hotline and other such 900 and 976 number services.

Those premium, charge per minute numbers are no longer a thing, but were all over the place for a bit.  It was a booming industry for about 15 years.  There was an episode of the Simpsons that featured such a number.

As time went on though, the demand for phone numbers eventually required the NANP to break the mold and allow any three numbers to be an area code.  That, and the advent of mobile phones have, in a way, removed the geographical references for phone numbers.  Yes, if you see 808, that is probably a Hawaii number, and 408 is Silicon Valley, while 415 is San Fransisco and part of the north bay, with 650 filling in the San Mateo peninsula in between 408 and 415.

But my dad has a 650 number and lives in the 916 area code, my mom has an 808 number and lives in the 408 area code, and I have a 916 number for work but rarely wander anywhere close to Sacramento and vicinity where that is centered.  While we live in the 408 area code, my wife has the phone number from our old condo in Blossom Hill, which she had migrated to her cell phone… a service that had just been introduced when she did it… so that her number indicates a dialing prefix in our area code that is nowhere near our billing address, much less where ever the phone might be.  And by the time I got my current cell phone number they were just handing out numbers with no relation to anything besides what was available.

There was a time when I would see a 408 number and know, from its prefix, the location of the central office to which it connected and the approximate geographic area that phone was located within.  Now though, not so much.  People move and don’t change their cell phone numbers because why bother?  There is effectively no long distance charges within the US… unless you’re calling from a landline.  All but the cheapest mobile plans include free long distance inside the country, and even per-minute plans charge the same per minute.  That phone number you’re dialing could be anywhere.

Still, the phone number system we have works.  For one thing, I couldn’t remember a 10 digit number off hand to save my life, but broken up into three distinct pieces, area code, prefix, and extension, somehow that combo actually sticks.

And it is actually an 11 digit number for many of, because if you live in an urban or suburban area with enough demand for phone numbers that they have overlayed another area code on top of your original one, you likely have to dial a 1, then the area code, then the prefix, then the extension.  But the 1 is pretty much a gimme.

When I first used a phone, I could dial anybody in our area code with a seven digit number.  Now I need 11 digits… and, honestly, I barely remember any phone numbers at this point because my iPhone remembers them all for me.  My brain, for whatever reason, remembers a lot of old phone numbers but very few new ones.