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This is the '''list of original North American Numbering Plan area codes''' of 86 plan areas as defined by [[AT&T]] in 1947.
This is the '''list of original North American Numbering Plan area codes''' of 86 plan areas as defined by [[AT&T]] in 1947.


In preparation for [[direct distance dialing]], [[AT&T]] and the [[Bell System]] developed the [[North American Numbering Plan]] in the 1940s. The plan divided the United States and Canada into numbering plan areas (NPAs) and assigned a three-digit dialing prefix to each. Over the course of the decade following introduction of these routing codes, local subscriber numbers were standardized to seven digits. This included a three-digit central office prefix, dialed as the first two letters of the local [[exchange names|exchange name]] and one digit, and the four-digit subscriber line number.
In preparation for [[direct distance dialing]], [[AT&T]] and the [[Bell System]] developed the [[North American Numbering Plan]] in the 1940s. The plan divided the United States and Canada into numbering plan areas (NPAs) and assigned a three-digit dialing prefix to each. Over the course of the decade following introduction of these routing codes, local subscriber numbers were standardized to seven digits. This included a three-digit central office prefix, dialed as the first two letters of the local [[exchange names|exchange name]] and one digit, and the four-digit subscriber line number.{{citation needed|date = July 2015}}


The original numbering plan defined the second digit of all area codes as either ''0'' or ''1'', to distinguish them from the local telephone exchange prefixes, which were assigned digits ''2'' through ''9'' in the second position. Area codes with a middle digit ''0'' (zero, ten dial pulses) were assigned to plan areas that covered an entire state or province, while jurisdictions with multiple plan areas received area codes having ''1'' (one, a single pulse) in the second digit.<ref>http://www.theatlantic.com/technology/archive/2014/02/our-numbered-days-the-evolution-of-the-area-code/283803/</ref> This permitted long distance calls to be dialed within the same area code as a seven digit subscriber number without the area code.
The original numbering plan defined the second digit of all area codes as either ''0'' or ''1'', to distinguish them from the local telephone exchange prefixes, which were assigned digits ''2'' through ''9'' in the second position. Area codes with a middle digit ''0'' (zero, ten dial pulses) were assigned to plan areas that covered an entire state or province, while jurisdictions with multiple plan areas received area codes having ''1'' (one, a single pulse) in the second digit.<ref>http://www.theatlantic.com/technology/archive/2014/02/our-numbered-days-the-evolution-of-the-area-code/283803/</ref> This permitted long distance calls to be dialed within the same area code as a seven digit subscriber number without the area code.{{citation needed|date = July 2015}}


The most prominent, frequently called population centers were assigned digit sequences with the shortest dial time on [[rotary dial]] telephones.<ref>[http://www.area-codes.com/area-code-history.asp Area Code History].</ref> The dialing time was determined by the amount of rotation of the dial that was needed to dial each digit. Digits 1 to 9 produced the corresponding number of pulses, and 0 resulted in ten pulses. For example, [[New York City]] was assigned area code 212 (five pulses), [[Los Angeles]] 213 (six pulses), [[Chicago]] 312 (six pulses), and [[Detroit]] 313 (seven pulses), while the area code with the lowest number, 201, produced 13 pulses.
The most prominent, frequently called population centers were assigned digit sequences with the shortest dial time on [[rotary dial]] telephones.<ref>[http://www.area-codes.com/area-code-history.asp Area Code History].</ref> The dialing time was determined by the amount of rotation of the dial that was needed to dial each digit. Digits 1 to 9 produced the corresponding number of pulses, and 0 resulted in ten pulses. For example, [[New York City]] was assigned area code 212 (five pulses), [[Los Angeles]] 213 (six pulses), [[Chicago]] 312 (six pulses), and [[Detroit]] 313 (seven pulses), while the area code with the lowest number, 201, produced 13 pulses.{{citation needed|date = July 2015}} Adjacent areas were generally assigned codes that were not easily confused with one another, to minimize wrong numbers.{{citation needed|date = July 2015}}


No codes of the form ''N00'', ''N10'' or ''N11'' occur in the original set, with N=2, 3, ..., 9. The series ''N00'' was used for non-geographic numbers, starting with intrastate toll-free 800-numbers in 1966.<ref>http://www.atlantatelephonehistory.info/part4.html</ref> ''N10'' numbers were originally [[Teletypewriter eXchange|teletypewriter exchanges]] and ''N11'' remains reserved for information and emergency numbers. No codes were originally assigned to Alaska and Hawaii, as neither were US states at the time, or Puerto Rico.<ref>http://www.lincmad.com/map1947.html</ref>
No codes of the form ''N00'', ''N10'' or ''N11'' occur in the original set, with N=2, 3, ..., 9. The series ''N00'' was used for non-geographic numbers, starting with intrastate toll-free 800-numbers in 1966.<ref>http://www.atlantatelephonehistory.info/part4.html</ref> ''N10'' numbers were originally [[Teletypewriter eXchange|teletypewriter exchanges]] and ''N11'' remains reserved for information and emergency numbers. No codes were originally assigned to Alaska and Hawaii, as neither were US states at the time, or Puerto Rico.<ref>http://www.lincmad.com/map1947.html</ref>


Initially, the codes were used by long-distance operators for trunk calls while preparations proceeded for end-customer [[direct distance dialing]]. The first customer-dialed call using an area code was placed on November 10, 1951, from [[Englewood, New Jersey]], to [[Alameda, California]].<ref>[http://www.corp.att.com/attlabs/reputation/timeline/51trans.html First direct-dial call]</ref> Direct distance dialing was gradually implemented throughout the continent. By the mid-1960s, direct distance dialing was commonplace in large cities.
Initially, the codes were used by long-distance operators for trunk calls while preparations proceeded for end-customer [[direct distance dialing]]. The first customer-dialed call using an area code was placed on November 10, 1951, from [[Englewood, New Jersey]], to [[Alameda, California]].<ref>[http://www.corp.att.com/attlabs/reputation/timeline/51trans.html First direct-dial call]</ref> Direct distance dialing was gradually implemented throughout the continent. By the mid-1960s, direct distance dialing was commonplace in large cities.{{citation needed|date = July 2015}}


==Original area codes==
==Original area codes==

Revision as of 20:39, 7 July 2015

This is the list of original North American Numbering Plan area codes of 86 plan areas as defined by AT&T in 1947.

In preparation for direct distance dialing, AT&T and the Bell System developed the North American Numbering Plan in the 1940s. The plan divided the United States and Canada into numbering plan areas (NPAs) and assigned a three-digit dialing prefix to each. Over the course of the decade following introduction of these routing codes, local subscriber numbers were standardized to seven digits. This included a three-digit central office prefix, dialed as the first two letters of the local exchange name and one digit, and the four-digit subscriber line number.[citation needed]

The original numbering plan defined the second digit of all area codes as either 0 or 1, to distinguish them from the local telephone exchange prefixes, which were assigned digits 2 through 9 in the second position. Area codes with a middle digit 0 (zero, ten dial pulses) were assigned to plan areas that covered an entire state or province, while jurisdictions with multiple plan areas received area codes having 1 (one, a single pulse) in the second digit.[1] This permitted long distance calls to be dialed within the same area code as a seven digit subscriber number without the area code.[citation needed]

The most prominent, frequently called population centers were assigned digit sequences with the shortest dial time on rotary dial telephones.[2] The dialing time was determined by the amount of rotation of the dial that was needed to dial each digit. Digits 1 to 9 produced the corresponding number of pulses, and 0 resulted in ten pulses. For example, New York City was assigned area code 212 (five pulses), Los Angeles 213 (six pulses), Chicago 312 (six pulses), and Detroit 313 (seven pulses), while the area code with the lowest number, 201, produced 13 pulses.[citation needed] Adjacent areas were generally assigned codes that were not easily confused with one another, to minimize wrong numbers.[citation needed]

No codes of the form N00, N10 or N11 occur in the original set, with N=2, 3, ..., 9. The series N00 was used for non-geographic numbers, starting with intrastate toll-free 800-numbers in 1966.[3] N10 numbers were originally teletypewriter exchanges and N11 remains reserved for information and emergency numbers. No codes were originally assigned to Alaska and Hawaii, as neither were US states at the time, or Puerto Rico.[4]

Initially, the codes were used by long-distance operators for trunk calls while preparations proceeded for end-customer direct distance dialing. The first customer-dialed call using an area code was placed on November 10, 1951, from Englewood, New Jersey, to Alameda, California.[5] Direct distance dialing was gradually implemented throughout the continent. By the mid-1960s, direct distance dialing was commonplace in large cities.[citation needed]

Original area codes

See also

References

  1. ^ http://www.theatlantic.com/technology/archive/2014/02/our-numbered-days-the-evolution-of-the-area-code/283803/
  2. ^ Area Code History.
  3. ^ http://www.atlantatelephonehistory.info/part4.html
  4. ^ http://www.lincmad.com/map1947.html
  5. ^ First direct-dial call
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