|
TelcoCD 2005 offers data at the following geographies:
- States (50 states + Washington DC) - 51
- MCD (Minor Civil Division) these are equivalent to the "town" - 35,164
- Zip Codes or ZCTA (Zip Code Tabulation Areas) - 29,048
- Area Codes (NPA - Numbering Plan Area) is the area in which the first three digit of the 10 digit phone number are the same - 260
- Area Code + Prefix (NPANXX - the first six digit of the 10 digit phone number) - 62,491
- Switches (also called Wire Centers) - the location (building) that houses the phone company equipment - 25,981
Switches are ONLY AVAILABLE ON THE TELCO 2005 PREMIUM VERSION
The area that is served (covered) by a switch is called the wire center serving area. One or more switches may combine to make up an exchange area and these are usually known by the name of the area that they cover. But some states do not have exchange areas so switches are an easier geography and thus the one we have included.
- The TelcoCD can also run a radius around a point (lat/lon), and it provides data on the NPANXX's within your radius
The Subarea (the area at which the data is expressed) is either the Area Code or Area Code + Prefix. The premium Version also has Switches. You can run a demographic data report for any of the three and create a DBF or CSV file for easy exporting into your own statistical database. However, maps are available for only the Area Code and Area Code + Prefix.
|
Area codes have real shapes to them (polygons) and can therefore be mapped as boundaries in TelcoCD 2005 and they can be exported into shape or mid/mif files to be imported into ArcGIS or MapInfo products.
Image is the Area Codes (NPAs) for the state of Michigan.
|  |
 |
The area code + prefixes are represented by their centroids. They do not have polygon boundaries because they are arithmetic calculations, thus we created a scatter chart and then weighed it out to determine the centroid of the field. The reason that the area code + prefixes don't have discrete boundaries is that multiple prefixes can be found at the same address or in the same block. For example your neighbor's house will have the same area code, but not necessarily the same next three digits as yours, they can have a difference Prefix. Phone companies create a new Prefix for every 10,000 phones or fewer (because the full phone number is NPA-NXX-xxxx so 9,999 is the most numbers that can exist in that format). The Prefix codes are heavily intermixed so instead of creating overlapping boundaries with holes in them we chose to express the "shape" of the Prefix as a "center of gravity" instead.
Image is the NPANXX for Chandler/Phoenix Arizona
|
b>Local Calling Areas (switches) are available as data only. A switch is described by its code and also by an associated rate center and a phone company.
We plan to generate a "Wire Center" version of TelcoCD 2005 in which we will have Switch boundaries generated. For questions about this please contact us at questions@geolytics.com or 800-577-6717.
|
