Probably more than you ever wanted to know about area codes

[unixronin]

From a discussion elsewhere on telephone systems and possible ways to let you dial a logically "nearby" phone using less keystrokes:

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Remember, enough of the phone number space is full that there are essentially no un-issued numbers in existing area codes any more.  ALL "new" phone numbers in existing area codes [with the probable exception of some recently-allocated area codes and some rural area codes] have been previously used, and we've gone from each town having a single exchange and big cities having several, to even smallish towns having multiple exchanges and major metropolitan areas having multiple area codes each, to parts of some major metropolitan areas having overlaid area codes because there aren't enough phone numbers in a single area code and they don't want to split the same area code again.  The pool of available-but-unused area codes itself is rapidly shrinking.

A little research yields:

"The format of an area code is NXX, where N is any digit 2 through 9 and X is any digit 0 through 9.  Initially, the middle digit of an area code had to be "0" or "1". When this restriction was removed in 1995, additional area code combinations became available.  There are 800 possible combinations associated with the NXX format.  Some of these combinations, however, are not available or have been reserved for special purposes."

Among these special purposes, it is noted that 37X and 96X have been "set aside by the INC for unanticipated purposes where it may be important to have a full range of 10 contiguous codes available", and the entire range of N9X has been "reserved for use during the period when the current 10-digit NANP number format undergoes expansion".  Codes with matching final digits (including N11) are reserved for special services.

That leaves 620 usable area codes.  By my best count, 384 of those are currently in use.  33 more have been planned but are not yet in service, for a total of 417 allocated area codes, leaving 203 available area codes for future expansion before they have to increase the number space.  Note that the N[01]X restriction in place up until 1995 limited the area code space to 160, minus the special area codes; subtracting N00 and N11 codes leaves 144 total available area codes prior to 1995.  In other words, in the 12 years since 1995, we have allocated twice as many new area codes as the total number of area codes available in 1995.  If we continue to allocate new area codes at that rate, even assuming a merely linear usage rate, we will exhaust the entire usable ten-digit space by about 2016; and if we make a real-world reasonable assumption about the probable shape of the usage curve, then 2012-2013 is a more likely estimate.

Comments

[unixronin.livejournal.com]

On the flip side, how are we doing with SSN's, which are also 10 digits?

It's worse than that, too, because those first three digits encode the issuing office, and there are not 999 issuing offices. Also, I know there is a theoretical premise built into the system that no social security number will ever be re-issued. (Ten digits probably seemed like plenty when the system was set up.) Whether that is actually honored any more, I don't know.

For "individuals", use the remaining 10 digits to assign a life-long phone number that goes with them no matter where they move ... it's like a hostname, mapping to an underlying "circuit" (like a CDMA phone's ESN). That underlying location could even change during the day ("when I'm at home, park my personal phone number at my house phone; when I'm on the road, park it at my cell phone; etc."). You'd just need to have some sort of service (comparable to a dynamic routing protocol) that tells you where a given individual number is currently parked. And, most people would probably just leave it at their cell phone all the time. Plus, you could have multiple individuals parked at the same circuit (everyone within a family, for example, parked at the same home landline phone).

Exactly such a system has been proposed at various times. Number portability is a baby-step along the way. Whether it'll actually ever get implemented in a form like that remains to be seen.

You could say that "10 digits is a lot to memorize for an individual, the current scheme means you only have to memorize 7 digits, which is right in the middle of the 5-9 digit range that is based on psychology data"... except that's not really relevant anymore because memorizing phone numbers is much less common than it used to be. Today, lots of people don't even know each other's phone numbers, they just have them programmed into their handset, and only ever see the person's name and the type of number (that person's cell phone, that person's home phone, that person's work phone, etc.). For individuals, my scheme sort of depends upon that -- you only ever know an individual's number when you first acquire it, and program it into whatever you use for a contacts list.

Exactly. There's basically two classes of phone numbers these days — ones you have to look up anyway, and ones you have on some form of memorized speed-dial.

One would certainly like to HOPE that when the time comes, instead of just patching the system, people would think carefully about the problem and completely revamp it in a single step calculated to maximize functionality and user-perceived backwards compatibility while minimizing disruption of services. But that's not an easy thing to do, and real-world experience says we'll get another band-aid patch and continuation of the trickle of incremental improvements. One thing I expect to see happen possibly sooner than other changes is to see the concept of "long distance" tolls just completely go away. Possibly even for international calls. Anywhere on the planet for one flat rate.



(As a side note, it boggles me that people have difficulty memorizing more than nine digits. I routinely memorize my 19 [total] digit credit/debit card numbers [23 if you count expiry date], and I used to have the value of pi memorized to 26 places when I was using it regularly. But I already know I'm an edge case.)