2001-01-03
Why Not Use 8-digit Local Numbers?
With the dizzying pace of area code splits, resulting in area codes the size
of a smallish postage stamp, one of the suggestions that often comes up is
"Instead of all these insane splits, why don't we just let the big cities
have longer local numbers?" Many other countries even have variable length
numbering schemes, where most small towns have 5- or 6-digit numbers, and
big cities have 7- or 8-digit numbers, or even a mix of number lengths
within a city or town.
The NANP is set up on a 3-3-4 numbering scheme
The entire North American Numbering Plan is constructed around the
fixed-length numbering scheme that each area code is three digits, followed
by a three-digit prefix and a four-digit line number. Those assumptions are
built into the NANP at many different levels, from administrative policy to
the actual wiring of telephone switching equipment.
The association of each prefix with a specific company's switch in a
particular central office is gradually eroding with the introduction of
Local Number Portability (LNP). In its most basic form, LNP allows a
customer to change Local Exchange Carriers (LECs) while retaining the same
number, so long as the location is the same, or at least within the same
rate center (town or portion of a city). In the future, however, LNP may be
expanded to allow the customer to retain the same number even when moving to
a different rate center -- possibly even to a different state.
However, even the limited version of LNP that is currently being implemented
is enormously complicated. Within areas that have LNP, every single call
requires a database lookup to determine the correct LEC and switch in order
to route the call. If LNP expands to a national or even statewide scope, the
added complexity in call routing will be staggering.
Europe (etc.) has variable-length numbers. Why can't we?
The fixed-length numbering scheme used in North America allows the
originating switch to reliably determine that the full destination number
has been dialed, and transmit the entire number to the network in a single
signalling block. In countries that have variable-length numbers, any call
outside the local area requires sending each digit individually to the
network, with an acknowledgement sent back from the destination switch when
a complete valid number has been received. It is substantially more
efficient to transmit a single 10-digit number than to transmit ten (or
eleven or nine) individual digits.
How about assigning a block of area codes to a big city?
One proposal often floated for dealing with the explosion of area codes in a
metropolis is to assign a block of consecutive area codes. Callers outside
the area would dial the normal 10-digit number, 1-NPA-NXX-XXXX. However,
callers inside the metropolitan area could dial the last digit of the area
code and then the 7-digit number, making effectively an 8-digit local
number.
For instance, let's say that we assign Los Angeles County the area code 59.
We could then map the existing area codes as follows:
213 becomes 592
310 becomes 593
323 becomes 594
562 becomes 595
626 becomes 596
818 becomes 598
597 is reserved for the split of 310 in 1999
599 is reserved for a future split, or spare capacity for the other 7
There are several flaws in this plan. First of all, these blocks of area
codes would have to be assigned in groups of ten, although only 8 of the
area codes could be used. If an area needed fewer than 8 area codes, the
extras would also be wasted, because it would be confusing to assign them
elsewhere. In the example here, we wouldn't want to assign 597 or 599 in
another area, but we also wouldn't want to assign 590 or 591 at all, since
that would be confusing. (There is also the issue that all codes with the
second and third digits the same -- for example, 599 -- are reserved as
"easy to recognize" codes for non-geographic purposes.)
Still and all, what happens about five years from now when Los Angeles
County needs its ninth area code? (Not counting the fact that a large
portion of northern Los Angeles County is already in area code 805, and
smaller portions are in 909, 714, and 760) Well, we just have to split area
code 59, and we're right back where we started.
There's also the issue of how we make the transition. Outside the area, it's
a simple and straightforward matter of permissive dialing. For a period of
several months, you can dial either 213 or 592, for instance, and then an
intercept recording will direct you to the new code. Inside the metropolitan
region, though, there would be strong pressure to allow permissive dialing
of either the old 7-digit number or the new 8-digit number. Unfortunately,
the only way to distinguish between 2NXX-XXX<pause>X and 2NX-XXXX is by
letting the switch time out if you dial only 7 digits -- the switch waits a
certain interval to see if you dial the eighth digit. If you make the
interval too short, then you dramatically increase the number of misdials;
if you make it too long, customers become annoyed at the long call setup
time.
There is also the issue of where we get these blocks of numbers. The example
above is entirely fictitious -- area codes with 9 as the second digit cannot
be assigned, because they are reserved for future expansion. There are, as
of this writing, only nine blocks of ten area codes that have no announced
assignments. Two of these (37X and 96X) are reserved for special purposes,
and it is unlikely that they would be released for something like our
example here. The other seven may have codes already reserved, and in any
case are likely to have codes assigned before long.
The bottom line is that the plan of assigning a block of area codes to a
large metro area is unworkable because it is inflexible and impossible to
implement without massive disruption, and it leaves no method of providing
further relief if needed in the future.
Massive costs of changing the phone number format
Any change in telephone numbering that breaks the assumption of 3-3-4
numbers will impose massive costs, both on the telephone companies and on
customers of all sizes. Every telephone switch in North America is built on
the assumption that numbers are 3-3-4, and changing that basic assumption
will be difficult, time-consuming, and enormously expensive. It will require
literally decades of planning. At this stage, a target date of 2015 would be
a tight schedule, and the total expense will run well into the billions of
dollars.
In addition, every company PBX assumes that numbers are 3-3-4, so those will
also have to be replaced, or at least given major (and expensive) upgrades.
Consider the costs and confusion that were created simply by breaking the
assumption that the middle digit of an area code is always 0 or 1!
Innumerable database programs are hard-wired to the notion of 3-3-4. Many
numeric pagers assume that numbers are 3-3-4 for display purposes, and the
display is often twelve characters, to accommodate ten-digit numbers with
two dashes. All of these pieces of customer equipment will be made less
handy, or even made obsolete. Again, we're talking about many billions of
dollars, just to upgrade the necessary equipment to continue functioning.
Asking businesses to make that sort of investment again requires many, many
years of advance notice.
The bottom line: billions of dollars and years of planning to make any
change on this scale.
The short-term solution
The short-term solution is to view telephone numbers, at least in large
metropolitan areas like Los Angeles, New York, and Chicago, as TEN-DIGIT
numbers. Think of the area code as more of a "super-prefix" instead of an
area code. Then assign area codes as OVERLAYS. How many people can tell you
the area code for an arbitrary address in Los Angeles County? Dozens of
communities straddle at least one area code boundary. There is already no
longer any meaningful geographic association between the area code and the
tiny chunk of land it serves -- area code 213 is already only 9 square
miles, but it will split again in 1998. With an overlay, every existing
customer gets to keep the same number. No new business cards, signs,
brochures, or other costly changes for businesses; no annoying changes for
residential customers. There has been strong customer resistance to overlays
because of the irrational fear of having to dial the entire 10-digit number
on every call, but in a place like Los Angeles, anything past your own block
is liable to be in a different area code anyway, and no one seems to be
unable to cope with the need to dial the full number on calls from Covina to
Compton, or Glendora to Glendale, or even western West Hollywood to eastern
West Hollywood. I grew up in an area that had only a single prefix. Every
number was 239-xxxx. Then a second prefix was added, and suddenly some
people had 233 numbers, and then later 661 and 387. As each new prefix came
into service, it was a bit unfamiliar, but it quickly became part of the
neighborhood. You might even see a business with a main number in the 233
prefix, but a 387 fax number; no big deal. The same will happen with overlay
area codes. Marylanders are gradually getting accustomed to seeing the first
few 240 and 443 numbers, but as they see more and more of them in the months
to come, the new area codes will lose their unfamiliarity and even their
novelty value and fall into the category of "just another number."
There are still situations in which geographic splits make the most sense.
For example, area code 512 in south Texas is expected to require relief
within the next one to two years. It currently serves two major cities,
Austin and Corpus Christi. It makes sense to split 512, giving each city a
separate identity numerically. Even some lopsided splits could make sense,
such as cutting Marin County into its own area code before instituting an
overlay in the remaining (San Francisco) area of 415. However, making any
further geographic splits in dense areas like Los Angeles, New York,
Chicago, Dallas, Houston, Atlanta, Fort Lauderdale, and Miami, is the
essence of absurdity.
The long-term solution
All area codes with '9' as the second digit are reserved for future
expansion of the North American Numbering Plan. I have outlined a specific
elaboration of the idea, proposing to move to both four-digit area codes and
four-digit prefixes. My plan would provide enough numbering resources to
allow every parakeet in Los Angeles to have separate numbers for his
cellphone, fax, and cellular fax. It would also have the side benefit of
allowing for a period of ten to twenty years without additional splits or
overlays, even in the fastest-growing metropolitan areas. For more details
about my proposal, please visit the future.html page on this site.
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Gl�ckliches Neues Jahr!
Happy New Year!
John
Keiner ist hoffnungsloser versklavt als derjenige, der irrt�mlich glaubt
frei zu sein.
There are none more hopelessly enslaved then those who falsely believe they
are free!
Johann Wolfgang von Goethe (1749-1832)
Toronto was the first city to adopt a new area code in Canada. The
metropolitan area was given the new "905" number and the city kept
the old "416" number. Alberta just recently split in half; the
larger city, Calgary, kept the old "403" number while the northern
half, containing the provincial capital, Edmonton, adopted the new
"780" number. I would suspect if there was a single national
telephone network it would not be difficult to adopt an 8 digit
local number, but each province has it's own telephone system, and
many cities still have their own local phone company. It would be
very difficult without the heavy hand of the CRTC (Canaidan Radio
and Telecommunications Commission; the national regulator for TV,
radio/cellular, and telephone). I suspect we have nearly as much
inertia as our American cousins, but at least we have a stronger
central government to knock us in a new direction... if they set
their minds to it, at least.
greg
