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| | North American Numbering Plan biography .ms |
 | | Area codes, or "number planning areas" ending in double digits, such as toll-free 800, 888, 877, and 866, personal 700 numbers, and high-toll 900 numbers, are reserved as Easily-recognizable codes (ERCs) and are not issued to actual areas. |
 | | In general, area codes were added either as "splits" (in which an area code was divided into two or more regions, one retaining the older area code and the other areas receiving a new code), or " overlays ", in which multiple area codes were assigned to the same geographical area. |
 | | After the remaining valid area codes were used up in expansion, in 1995 the rapid increase in the need for more area codes (both splits and overlays) forced NANPA to allow the digits 2~8 to be used in new area code assignments, with 9 being reserved as a "last resort " for potential future expansion. |
| north-american-numbering-plan.biography.ms (2065 words) |
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