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Telephone
Area Codes in North America
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Telephone
numbering plan: A telephone numbering plan is a plan
for allocating telephone number ranges to countries, regions,
areas and exchanges and to non-fixed telephone networks such
as mobile phone networks. Dial plans should not be confused
with numbering plans. A closed numbering plan, such as found
in North America, features fixed length area codes and local
numbers. An open numbering plan, as found in assorted countries
that have not yet standardized, features variance in length
of area code or local number, or both. The rules for dialing
the numbers assigned by the numbering plan vary by defining
which digits need not always be dialed (codes) and digits
that must always be dialed (local number).
Why aren't numerically
sequential area codes given to geographically adjacent areas?
The assignment of telephone
area codes may seem random but actually it's pretty sensible.
The North American Numbering Plan, of which the area codes
are a part, was worked out in the late 1940s to ensure standardized
numbering nationwide, helping to make direct-dial long distance
possible. (Prior to that time, one had to go through an operator,
that is 'trunk call').
On the rotary-dial phones then
in use, dialing a nine (9) took a lot longer than dialing
a one(1), which tied up expensive switching equipment. So
AT&T assigned "low dial pull" numbers to the
markets with the most telephones and thus presumably the highest
number of incoming long-distance calls. New York got 212,
Chicago 312, L.A 213, Detroit 313, Dallas 214 and so on. Strangely
Washington D.C got 202 and Maryland 301 (Zero, remember, has
the highest dial pull of all) may be this anomaly represented
some "smoldering vendetta" against the Eastern Seaboard
:-) Anyway.
The issue of dial pulls became
academic with the introduction of touch-tone phones in the
early 1960s. Since then the guiding principle behind the assignment
of new area codes has been to make the new number as different
as possible from the adjacent old ones in order to avoid confusion.
That's why the split of New York's 212 produced 718, L.A's
213 begat 818 and Chicago's 312 was joined by 708 (which then
was split again and we got 630 for Westmont and surrounding
areas, 847 for Schaumburg etc). This non-consequent nature
though looks illogical, is meaningful in a way.
One more thing. Originally
the switching system required that the middle digit in each
code be a one (1) or a zero (0). You can see it in San Jose,CA
(408); San Diego,Ca (619); Philadelphia,PA (215); Boston,MA
(617); Portland,OR (503) etc. But this meant there were only
152 numbers available. By the early 1990s, all but a handful
of these had already been spoken for. To get around this limitation,
phone companies around the country have been implementing
"Dial-1" service, which requires you to dial 1 at
the start of any direct-dial long distance call. This permits
the use of additional digits in the middle position, giving
us a total of 792 potential codes, which ought to hold us
for a while.
Emergency Number 911; But Why?
This topic is about the Emergency
Number 911. But no hurry, read at your leisure :-))
Have you ever wondered
why 911 was chosen as the emergency code throughout the United
States?
Prior to the 1960s, there was
no universal number to call for emergency help. In 1967, the
Federal Communications Commission met with AT&T to establish
such a number, according to the National Emergency Number
Association (NENA). But why did they choose 911? Why not 422
or 111?
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There are several reasons
why 911 was chosen.
It's a short, easy to
remember number, but more importantly, 911 was a unique
number.
It had never been designated
for an office code, area code or service code.
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There were emergency numbers
existing but not uniform. In one state 113 was for emergency
and 411 was for directory assistance, in another state 411
was for emregency and so on. Also, numbers like 111, 211,
311, 411 etc were in use locally in each state, for different
services though. Then there is bit of "kanjusi"ness
or business-mindedness behind this. If you see the touch-tone
dial pad on your phone, you will realize that the numeric
key "1" doesn't have an alphabet. Also for 9, the
alphabets are W, X and Y - less frequently used letters. So,
telephone companies can allot "alphabet possible numbers"
to such premium customers and corporates (for additional price)
and retain no-alphabet keys to "free" services like
this!!! Sounds "maha chaalu"? :-)
| Existing
N11 Code Assignments by FCC |
| 211 |
Assigned
for community information and referral services. |
| 311 |
Assigned
nationwide for non-emergency police and other government
services. |
| 411 |
Unassigned,
but used virtually nationwide by carriers for directory
assistance. |
| 511 |
Assigned
for traffic and transportation information. |
| 611 |
Unassigned,
but used widely by carriers for customer care or repair
service. |
| 711 |
Assigned
nationwide for access to Telecom Relay Services. |
| 811 |
Unassigned,
but used by many local exchange carriers for business
office use. |
| 911 |
Assigned
nationwide for emergency services. |
On February 16, 1968, Alabama
Senator Rankin Fite made the first 911 call in the United
States in Haleyville, Alabama. The Alabama Telephone Company
carried the call. A week later, Nome, Alaska, implemented
a 911 system. In 1973, the White House's Office of Telecommunication
issued a national statement supporting the use of 911 and
pushed for the establishment of a Federal Information Center
to assist government agencies in implementing the system.
When we dial 9-1-1, the call
is automatically forwarded to a Public-Safety-Answering-Point
(PSAP), also called a 911 call center. Typically, the caller
will tell the 911 operator about the emergency and his or
her location. From 2001, most areas are also serviced by Enhanced
911, which allows the operator to trace the phone call and
access the address that the call is coming from.
Links of Interest:
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