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Technical Specifications for the Area Code Database

NPA - NXX Area Code Database

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Database Technical Specifications


Field Name Data Type Description
NPAChar(3)Area Code (NPA = Numbering Plan Area)
NXXChar(3)Three digit local number prefix (X=2-9, X=0-9).Generally 201 thru 999.
CountyPopIntegerEstimated population to nearest 1000. This is a very rough estimate based on 1990 census data!
ZipCodeCountIntegerApproximate population of the ZIP code.
ZipCodeFreqIntegerPercent frequency of occurrence of this Zip Code in the NPANXX area.
If = 0, then unknown
If = -1, then the ZIP Code is the most frequent, but % unknown
If = -2, then the ZIP Code is the second most frequent, but % unknown
LatitudeDecimal(12, 8)Latitude of record for the central office
LongitudeDecimal(12, 8)Longitude of record for the central office
StateChar(2)Two letter USPS state abbreviation
CityVarChar(255)Popular or political name of city
CountyVarChar(255)Name of county
TimeZoneVarChar(255)Offset from GMT (5=East, 6=Central, 7=Mountain, 8=West, etc..)
ObservesDSTVarChar(255)1 = Observes DST (Daylight Saving Time) during the normal DST observance period, 0 = Does not observe DST at all. Some areas of the country such as AZ (except for the Navajo Nation), HI, GU, PR, VI, and parts of IN do not observe DST.
NXXUseTypeVarChar(255)Primary use designation. L=Landline, W=Wireless (all wireless; pagers, cellular, PCS, etc.)
Note that some NXXs may be subdivided between landline and wireless. This is simply the reported type.
NXXIntroVersionVarChar(255)Version of this product that NXX first appeared.
ZipCodeVarChar(255)ZIP Code (United States) (five digits)
NPANewVarChar(255)New Area Code. During the permissive dialing period, the old area code map still be displayed in the "NPA" field. If blank, then there is no record (yet?) of a split. If non-blank, then associated NXX is freshly relocated to this new NPA and the NPA in the "NPA" field (above) would be the old one
FIPSVarChar(255)Census Bureau FIPS code (ID) for the tract of the central office
LATAVarChar(255)Local Access Transport Area
OverlayVarChar(255)1 = NPA recent overlay, blank = Not an overlay
RateCenterVarChar(255)Ten character Rate Center name for CO. Blank = Rate Center name unknown.
SwitchCLLIVarChar(255)This field is now blank and will be removed in a future version of the database. The data will no longer be available.
MSA_CBSAVarChar(255)Census Bureau Names for the metro area of the central office
MSA_CBSA_CodeVarChar(255)Census Bureau ID numbers for the metro area of the central office
OCNVarChar(255)Four-character alphanumeric field identifying the NPA-NXX code-holder and/or service provider.
CompanyVarChar(255)The company name.
CoverageAreaNameVarChar(255)The name of the area this NPA-NXX Covers. This is primarily the city name but other Alias Names may be used.
NPANXXChar(6)The NPA and NXX combined.
FlagsVarChar(35)Any flags indicating specific things about this data record.
StatusVarChar(35)Indicates if this NPANXX is in active use ("Active" or "Inactive")