Telecom Informer
by The Prophet
Hello, and greetings from the Central Office! It's spring, my least favorite time of year because I'm sneezing up a storm. Tree pollen always hits me the worst, and it starts the earliest and goes the longest. Of course, given the coronavirus panic here in the Puget Sound area, every time I sneeze, people around me give me worried sidelong glances. So, my work is taking on particular urgency since it's entirely possible that I could be quarantined at any time! I'll get to it right after I finish my break and a little "service monitoring" of the local ambulance company.
Today, we're running a test of our exchanges in the 564 area code overlay in western Washington. "Wait a minute," you might say. 564? Is that even a thing? And what's an overlay, anyway?" You'd be correct to note that there are nearly no subscribers with numbers in the 564 area code. However, the infrastructure is in place, test numbers exist, and phone companies have even laid claim to some of the best exchanges. Other than an annual exercise to ensure that calls are still routing, the 564 area code continues to lay mostly dormant - but not for long.
Since their inception, area codes were historically assigned by the Bell System to a fixed geographic area via the NANPA, or North American Numbering Plan Administrator. Exchanges were further historically assigned 10,000 numbers at a time. Growth in new area codes was slow and steady, and the original design of the area code system (which used three-digit numbers from 201 to 919, with only a 0 or 1 in the middle) allowed for plenty of growth, which mostly tracked the growth of the population in North America. Decades went by without many changes in area code maps. The name of the company running NANPA changed to BELLCORE in 1983, but the people doing the work, for the most part, didn't. They were drawn from Bell Labs and the regional Bell companies after the breakup of the Bell System.
The area code landscape began to change in the late-1980s with the introduction of Competitive Local Exchange Carriers (CLEC), pagers, faxes, voicemail, VoIP, and cellular phones.
This massively accelerated in the 1990s as people went from having one or two phone numbers to five or more (such as a home line, modem line, business line, fax line, and mobile phone), and from doing business with one phone company to - in some cases - several. In fact, from the 1990s until the early-2000s, hardly a month went by without an area code split somewhere in the North American Numbering Plan (which is the parts of the U.S., Canada, and the Caribbean represented by country code 1). New area codes marched across the country, usually issued in "geographic splits." Despite reclaiming a handful of area codes from Telex services (which were retired), and despite pushing Mexico's Telnor out of the North American Numbering Plan and into country code 52, NANPA ran out of area codes using the historical format in 1995. Two new area codes, 360 and 334, were introduced. And now, despite number conservation measures, area code 360 is nearly exhausted and will be overlaid by a new area code, 564.
Before we get to that, it's worth reviewing a little history. Long distance used to be a very big deal - calling outside of your local area was expensive (often very expensive) and generated large profits for phone companies. Area codes always had a "0" or a "1" in the middle, could never have the middle digit at the end (so for example, no 200 or211), and for the sake of convenience, it was a generally accepted convention not to assign the same numbers to exchanges as existing area codes. The reason for this was when making long distance calls within the same area code, you generally only needed to dial a "1" (for long distance) plus the seven-digit number.
However, allowing this convenience meant that fully 144 exchanges had to be reserved (every potential area code, meaning every number with a "0" or "1" in the middle from 201 through 919), because otherwise there would be no quick way for the phone system to differentiate between long distance calls within the same area code (using 1+seven-digit dialing) and long distance calls to another area code.
With the explosive growth in phone numbers, the generally accepted solution was simply to do a "split."
Along a geographic boundary that was defined by telephone rate centers, NANPA would propose to split an area code in two. For example, in 1959, the 415 area code was split into 415 and 408. However, splitting an area code created a major disruption for people each time they were forced to move to another area code. Business owners had to update business cards, stationery, and advertising. People had to notify their contacts of the new area code as well. And bear in mind, this was in an era where the normal way to update people was either to make an expensive long distance toll call or send them a letter in the mail!
Prior to implementing a split, a number conservation method was possible: over 1.4 million phone numbers could be freed up by assigning the same numbers to exchanges as used by area codes. However, this forced a change to dialing patterns: eleven-digit dialing became required for all long distance calls (1-NPA-NXX-XXXX).
You should have heard the howls of protest from owners of fax machines that this decision caused in the business office, but it allowed us to conserve the 206 area code for much longer than would otherwise have been possible. Moving to 11-digit dialing for all long distance calls further enabled the adoption of area codes without a "0" or "1" in the middle, so area codes like 360, 253, and 425 (three of the four area codes currently in use in western Washington, along with the 564 overlay) became possible.
There is another problem that can be solved by conservation: filthy CLECs and tiny providers wasting entire exchanges on a handful of customers.
The Telecommunications Act of 1996 created a massive explosion of companies who were allowed to ask for number assignments from NANPA. Naturally, it was almost free to get these, and there was no requirement to have any real subscribers, so every CLEC, paging company, mobile phone company, VoIP provider, and who knows what else snapped up exchanges for their potential (but non-existent) customers, quickly exhausting area codes. Limiting assignment to "thousands block," where numbers are assigned by NPA-NXX-NXXX instead of NPA-NXX-XXXX meant that instead of wasting 10,000 numbers, small providers would "only" waste 1,000 numbers.
Number conservation, however, only goes so far and eventually the growth does require either a geographic split or an overlay.
What's an overlay?
That's what we are doing with area code 564. It's just an additional area code for the same geographic territory, meaning that nobody has to change their existing phone number. When the 360 area code is eventually exhausted (it's very close to exhaustion, but has been managed closely with number conservation procedures), telephone service providers will start assigning new numbers in the 564 area code.
However, this creates another problem: seven-digit dialing doesn't work anymore because local calls can be in both area codes. In 2017, 10-digit dialing was mandated in the 360 area code to enable the 564 overlay. This created fewer problems than expected because it had been supported for years prior, and these days, most subscribers are calling on mobile phones (which require 10-digit dialing) instead of landlines. Although area code splits are still possible, the loss of seven-digit dialing is far less of an issue for subscribers than it once was. Many state public utility commissions, in fact, have mandated that future area code introductions must be performed as an overlay.
And with that, my test just passed, and my "service monitoring" just revealed that another friend is heading to the hospital.
I won't be visiting - but HIPAA be damned, I'll be calling from a landline phone! Stay healthy this spring, and the next time a call doesn't work from a landline by dialing only seven digits, you'll know why!