TELECOM Digest OnLine - Sorted: Re: Telephone Area Codes and Prefixes

Re: Telephone Area Codes and Prefixes

Neal McLain (
Sat, 10 Feb 2007 00:10:15 -0600

Joe Tibiletti <> wrote:

> I have testified before the Public Utility Commission of
> Texas -- one of the last states to have this jurisdiction
> placed in one organization under state control.

What do you mean by "one organization"?

If you're referring to an organization that regulates all (or almost
all) utilities, Texas isn't the only state. Every state has some sort
of utility regulatory agency (although they go by variety of names: ). Indeed, Texas is an oddball in this
respect: the TPUC regulates all utilities except natural gas; the
Texas Railroad Commission regulates natural gas; and the Texas DOT
regulates railroads.

If you're referring to an organization that regulates landline
telephone service, again, Texas isn't the only state. Almost every
state regulatory agency (by whatever name) regulates landline service
(I say "almost" because there's probably an exception somewhere; I've
just never heard of one).

If you're referring to an organization that assigns area codes, no
state, not even Texas, does this. Area codes in the United States are
assigned by NANPA ( ), and implemented by the state
(or territorial) regulatory agency. In every state, including Texas,
the state agency determines the *method* of area code relief (overlay,
split, or boundary realignment), and it can *request* specific area
codes.[*] But NANPA makes the final decisions on code assignments.

> The matter was the breakup of the then 512 area code with
> outlying areas to the state capital going to a new code of
> the N, (2-9), N -- ...

Actually, the format was N,(2-8),X. No area code can have 9 as the
middle digit; these codes are reserved for some unspecified future use.

> EVENTUALLY THE SECRET WAS OUT AS 361. They had their minds made
> up as to the outcome, but I put in my two cents worth.

NANPA had probably assigned 361 to Texas as a relief code long before
the TPUC even held hearings.

When NANPA assigns an area code, it has to consider several

- An area code can be used only once. A new area code can't conflict
with any other area code anywhere in the United States, Canada, Bermuda,
US territories in the Pacific, or a hodgepodge of geopolitical entities
in the Caribbean.

- An area code can't (or at least shouldn't) conflict with any central
office code within the area code; thus, for example, 573-573 would be
a prohibited combination. Consequently, when a new area code is
assigned, it must be selected from the list of presently-unassigned
central office codes. That list is likely to be short: if an area
code needs relief, it's already running out of central office codes.
(And yes, I'm aware of the 847-847 exception to this rule.)

- An area code can't conflict with any of several reserved
combinations: N11, N9X, NYY (second and third digits the same),
370-379, 456, 521-529, 555, 880-889, 950, 960-969.

If you apply all of these constraints to any given area-code relief
situation, you end up very few usable possibilities. In order to
avoid ending up with zero possibilities at some future date, NANPA has
established "Geographic Relief Codes" -- two or three codes held in
reserve for each state for possible future use. To ensure that these
codes remain available, they are never assigned as central office
codes within the state.

I suspect that 361 was one of these Geographic Relief Codes. I
wouldn't be surprised if it was assigned back when the 512/210 split
was under consideration.

> Here are my suggestions which are still today applicable.

> 1. Place all government telephones on their own area code...

Somebody here on TD once suggested splitting 202 by putting the
federal government in 666.

> In another comment cell phones are placed upon special area
> codes in Chicago and NYC.

NYC yes, Chicago no.

This issue invariably comes up in area code relief proceedings: if the
wireless (paging, cellular, and PCS) companies are using up all the
numbers, why not put them in their own "service-specific" area code?

The New York PSC adopted a service-specific overlay in New York City
in 1992 when 917 was overlaid on 212 and 718. The wireless companies
didn't like it because that "funny" area code put them at a
competitive disadvantage. Furthermore, reaching a 917 number from 212
or 718 required 11-digit dialing, while intra-area code numbers were
dialable with seven digits.

The next attempt to implement a service-specific overlay wound up in
the FCC's lap. In this case, Ameritech wanted to overlay 630 on 312
and 708 in the Chicago area. The wireless companies protested to the
FCC, asserting that service-specific overlays were not "competitively
neutral." The FCC eventually ruled that Ameritech could implement 630
as an all-services overlay or a split, but not as a service-specific

> 2. Give a fourth number (digit) behind the present area code
> three digits based upon the clock: with 0 being north of center
> of code area or city center, 3 to the east, 6 to the south, and
> 9 to the west.

If we're going to add any digits, I'd suggest adding a check digit to
prevent wrong numbers. Similar to UPC codes.

> 3. Give an additional digit to all numbers based upon use,
> e.g. 1 for cell, 2 for fax 3 for internet access, etc.

That sounds like another "service-specific" scheme. Furthermore, how
would a telco know what a given landline would be used for? Phone?
Answering machine? Fax? PC modem? Alarm system? TiVo? All of above?

If we're going to have any type of service-specific coding, I'd suggest
a code for coin phones.

> As to archives and comments of telephone number configurations,
> the prefix Zenith was used in the 1950's for non dial telephones
> in Pacific Palisades area of LA.

Zenith (and Enterprise) were used throughout the country for
operator-assisted calls to businesses willing to accept charges. I
suspect that Zenith was chosen because it couldn't be dialed.

> Chicago had in the same period a 2L and 6N in some sub-urban
> area numbers in the same period.

Are you sure? That totals eight digits. Source?

> Not all possible combinations were used in all area codes,
> while several private NXX -- such as KRypton was used in
> Houston, Texas, for the Humble Building...

Well, I guess that's better than KRemlin.


Combinations in the form 58X were widely used as far back as the
1950s. In point: St. Louis (LUcas); Chicago (JUniper). Mark Cuccia's
post "Recommended 'EXchange' Names" (TD 25:118, 03/26/06) lists the
following 58X combinations: JUniper, JUno, JUstice, LUdlow, LUther.

> Use of NXX which are identical to area codes.. this really
> confused subscribers, for example 512 the former area code of my
> home city of Victoria, Texas, prior to 361, was used as an
> exchange in the LA area in Gardena, another use of this knid was
> 708 (Rochester MN). In Austin, Texas, my NXX was 310 -- the
> area code for Beverly Hills...

Well, we exhausted the original 144 area codes in 1994, so we had to
adopt interchangeable area codes. Every area code introduced since
01/01/1995 is identical to a central office code in dozens of other
area codes.

> If one is familiar with telephone numbering issuance one can
> tell when a telephone number was issued in many cases.

> Issuance of numbers woulds be as follows: at time of dial
> switchover 5N (N-NNNN) then 1L - 4N -- uncertain whether
> all letters were used or not ...

Not necessarily. Some SxS exchanges used four-digit numbers (or four-
and 5-digit intermixed). In point: Ann Arbor.

> ... the exchanges 2L-4N followed by 2L-5N, or in Chicago 2L-6N.

Once again: are you sure about eight-digit numbers? Source?

> Note the initial digit in 2L-5N was not a 1 or a 0.

Neither was the second digit. Which is why N1X and N0X combinations
were not used for central office codes. Which (conveniently) is why
they were available in 1947 for use as area codes.

> then 2L-4N disappeared and 2L-5N took on 0 or 1 with 4 N, then
> 7N (except for NXX that were N(1 or 0) in second position or
> third position) 624, but not 604 7N with second digit 1 or 0
> being issued with other numbers e.g 510 7N with NXX including 00
> in second and third position. ef.g. 200 break up of area code.

I don't follow that sentence.

[*] Many states have requested specific (vanity) area codes. Lexington,
home of the University of Kentucky, is in UKY. Knoxville, home of
University of Tennessee's Volunteers, is in VOL. In Florida, Daytona
Beach has FUN, Miami gets SUN, and Cape Canaveral does the 321 countdown.

Several Caribbean entities have commemorated themselves: Anguilla
(ANG), Antiqua (ANT), Bahamas (BHA), British Virgin Islands (BVI),
Grenada (GRE), Puerto Rico (PTR), St. Lucia (SLU), St. Vincent and the
Grenadines (SVG), and Trinidad and Tobago (TNT). [Thanks to Mark
Cuccia for this list.]

But Nevada couldn't get 777, so it had to settle for 775. Two cherries
and a lemon.

In some area codes, unintentional vanity equivalents have arisen. In
Chicago's northern suburbs, every VIP carries a BAG. Canada's northern
territories are at the TOP of the world. In Utah, 385 spells ... well,
I'll let you figure that out.

Neal McLain
Brazoria, TX
Area code 979, formerly 409, formerly 713.

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