Overlay

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Overlay plan. - In telephony, especially in North America, an - overlay plan - is the practice of introducing a new area code by applying it onto a geographic area that is already occupied by one or more existing area codes, resulting in two (or more) area codes serving the same area.
Contents
Methodology
1.1Rapid growth
1.2Reluctant solution
1.3Compromise
1.4Popularity
Types of overlays
Number pool management
See also
References
External links
Methodology
Prior to the introduction of overlay plans, the method of introducing new area codes (also known as numbering plan areas or NPAs) in a region was to divide the existing territory of one area code into two (or more) pieces, allowing the more established or developed section to retain the original area code, and changing the numbering space of the other section(s) to have a new area code. For example, the original area code for the entire state of Washington was 206; today 206 applies to only the city of Seattle and immediate vicinity. This practice became known as a split plan.
Rapid growth
Urban sprawl accelerated the rate of expansion of metropolitan areas, and multiple split plans have caused the geographical area of a given area code in those regions to shrink. Also, the rapid growth in popularity of mobile phones, in addition to regular land line growth, has increased demand for new phone numbers even more.
The rise in popularity of mobile phones has added to the pressure against split plans, as an area code change affecting the exchange in which a cell phone is based requires the wireless carrier to reassign the number of every device based in those areas.
Reluctant solution
To alleviate complaints about such changes, in 1992 the telecommunication industry began to introduce "overlay plans" as a means to introduce new area codes. In this model, one fixed geographic area would concurrently have multiple valid area codes throughout. This plan's main benefit, which addressed many of the issues causing resistance to split plans, was that all existing phone numbers remained unaffected by the new area code. Newly-assigned numbers in the overlay plan areas would have the new area code. As a result, two telephones, located next to each other in the same building or house, could have different area codes. New York was the first area to employ this solution, using the 917 area code in addition to the older 212.
Compromise
However, overlay plans introduced a new inconvenience: mandatory 10-digit dialing (i.e., the area code must be included), even for local calls, in the affected area. This and the difficulty of remembering all the area codes in a geographic area made overlay plans only marginally less unpopular than split plans. It should be noted that 10-digit dialing is not a technical requirement but a U.S. Federal Communications Commission (FCC) mandate to promote fairness among telephone companies. [
Popularity
Overlay plans have been used much more widely in some areas than others. For example, the northern third of Ohio is covered by two large overlay complexes, as is northern Georgia. Connecticut, Illinois, Oregon, New Jersey, Massachusetts and Maryland have also used overlays heavily, and are (or soon will be) completely or mostly overlaid. In California, on the other hand, only four of 27 areas have overlays, and all were very recently implemented.
The first example of an entire state previously only served by a single code being overlaid was in West Virginia.
Overlays have also generally been more popular in Canada, with all of British Columbia and Alberta and most of Ontario and Quebec are currently (or soon will be) overlaid.
Types of overlays
The North American Numbering Plan Administration recognizes different forms of overlays:
Distributed overlay - in which an entire existing area gains another area code serving the entire area. Most overlay plans involve this method.
Single concentrated overlay - in which only the high-growth portion of an existing area gains a second area code.
Multiple concentrated overlay - in which the entire existing area gains multiple additional area codes, each of which serves a different subsection of the original. There are no known examples of such being implemented in the NANPA.
Multiple-area distributed overlay - in which two or more area codes gain a single new area code covering such an area. Examples include 872 in Chicago, Illinois (over 312 and 773) and 587 in Alberta (over 403 and 780).
Boundary-extension overlay - in which a neighboring area code (either an overlay code or single primary area code) is expanded to serve the area as well. Examples include 321 over 407 in central Florida and 778 over 250 in British Columbia.
Number pool management
The persistent unpopularity of new area code creation, whether by split or overlay plans, led to a change in the rules of number block allocation, in order to conserve the pool of available phone numbers. This change, which allowed for the assignment of smaller number blocks, is commonly known as number pooling. This has noticeably slowed the need for area code growth, but not completely. For example, the Western Washington area narrowly avoided needing an overlay in 2001. Area code 564, originally planned for introduction in October 2001, was canceled in August 2001 after state regulators determined that the existing number pool had begun to be used more efficiently.
See also
List of area code overlays
Interexchange carrier
Telephone exchange
Telephone numbering plan
North American Numbering Plan
Exhaust date
References
- ^ - FCC. "Area Codes: Frequently Asked Questions". Archived from the original on May 11, 2009. http://web.archive.org/web/20060615015544/http://www.fcc.gov/Bureaus/Common_Carrier/Factsheets/areacode.html
FCC FAQ concerning area codes at the Wayback Machine.
FCC FAQ - Carrier Identification Codes (CICs) and Seven-Digit Carrier Access Code (CAC) Dialing
References from: Overlay_plan Wiki
US
List of area code overlays

An - area code overlay - is a North American area code which is located in the same geographic location as at least one other area code. They are determined and regulated as part of the North American Numbering Plan to increase the number of available phone numbers in a province, state or region. [

List of area code overlays
The North American Numbering Plan Administration maintains the definitive list of overlay plans of current and proposed area codes and overlays in the United States. [
Current
224 overlays 847 in the northern suburbs of Chicago, Illinois.
226 overlays 519 in Southwestern Ontario.
234 overlays 330 in the Akron-Canton and Warren-Youngstown areas in Ohio.
240 overlays 301 in the Washington, D.C. suburbs and panhandle of Maryland.
267 overlays 215 in the greater Philadelphia area and its surrounding suburbs.
281 and 832 overlay 713 in Greater Houston. Originally, 281 was a pure geographic split from 713, but when 832 was added as an overlay, 281 was converted to an overlay.
289 overlays 905 in the Greater Toronto Area, Hamilton and the Niagara Peninsula in Ontario.
321 is used in part as an overlay of 407 in Orlando, Florida.
331 overlays 630 in the western suburbs of Chicago, Illinois.
339 overlays (parts of) 781 in Massachusetts.
347, in 718 areas for the Bronx and Queens boroughs of New York City.
351 overlays 978 in Massachusetts.
424 overlays 310 in the southwestern part of Los Angeles County, California.
430 overlays 903 in northeast Texas.
438 overlays 514 on the Island of Montreal, Quebec.
442 overlays 760 in the southeastern part of California.
443 overlays 410 in Baltimore, its suburbs, and the Eastern Shore of Maryland.
469 and 972 overlay 214 in the eastern portion of the Dallas/Fort Worth Metroplex (including the city of Dallas). As in the Houston situation discussed above, 972 was originally a geographic split from 214, but was converted to an overlay once 469 was implemented.
484 overlays 610 in eastern and parts of southeastern Pennsylvania.
551 overlays 201 in northeastern New Jersey.
567 overlays 419 in northwest Ohio, including Toledo and Lima.
571 overlays 703 in Northern Virginia.
587 overlays area code 403 in southern Alberta and area code 780 in northern Alberta (Canada).
636 overlays area code 314 in the western suburbs of St. Louis, Missouri.
646, in the area code 212 areas for the Manhattan borough of New York City.
647 overlays 416 in the City of Toronto, Ontario.
657 overlays 714 in northern Orange County, California.
678 overlays both 404 and 770 in metro Atlanta.
682 overlays 817 in the western part of the Dallas-Fort Worth Metroplex, including the city of Fort Worth.
720 overlays 303 in the Denver, Colorado area.
747 overlays 818 in the Los Angeles, California area.
754 overlays 954 in the Fort Lauderdale, Florida area.
769 overlays 601 in central Mississippi.
774 overlays (parts of) 508 in Massachusetts.
778 overlays 604 and 250 in British Columbia
779 overlays 815 in Northern and North Central Illinois. Some of the larger cities affected are Rockford, Freeport, and Kankakee.
786 is a concentrated overlay of area code 305 in Miami-Dade County, Florida. It does not include the 305-only Florida Keys.
848 overlays 732 in central New Jersey.
849 overlays both 809 and 829 in the Dominican Republic.
857 overlays (parts of) 617 in Massachusetts including Boston, Cambridge.
862 overlays 973 in northern New Jersey.
872 overlays 312 and 773 in Chicago, Illinois.
878 overlays 412 and 724 in metro Pittsburgh.
917, mostly for cellular phones, pagers, and voicemail in both 212/646 and 718/347 areas.
938 overlays 256 in northern Alabama.
939 overlays 787 in Puerto Rico.
947 overlays 248 in Oakland County, Michigan.
971 is a concentrated overlay of area code 503 in northwestern Oregon, including the Portland and Salem areas. On April 27, 2008, the coastal area of Clatsop and Tillamook Counties, which had previously been exempted from the overlay and used only 503, were added to the overlay.
980 overlays 704 in the Charlotte metropolitan region.
Proposed
236 proposed as a future overlay in British Columbia after 778 is exhausted.
343 will overlay 613 in Ottawa and surrounding Eastern Ontario beginning in 2010.
Area code 385 will overlay 801 in Utah, starting as early as March 2009. [4
Area code 447 is planned for overlay of 217, with no precise time frame for integration.
Area code 464 is also reserved for 708, to be integrated once the original area code is exhausted.
470 will supplement the 678 overlay already present for 404 and 770 in Metro Atlanta. The new area code has existed since 2001-09-02, but will not be used until all assignable 678 NXX codes are exhausted. [5 .
475 planned to overlay Connecticut area code 203.
564 planned for Washington area code 253; this plan is suspended, as 253 is not estimated for exhaust until 2025. [6
531 will overlay area code 402 in eastern Nebraska.
Area Code 679, planned to overlay 734 in Michigan.
681 will overlay 304 in West Virginia starting in 2009
825 proposed as a future overlay in Alberta after 587 is exhausted.
835 proposed to overlay 610 and 484. This plan has been suspended by the Pennsylvania Public Utilities Commission. [7
959, for 860 areas. Proposed 1999, [ but withdrawn.
Area code 984 is planned for overlay of 919. This was originally planned in 2001 to take place in 2002, but has been postponed due to implementation of number pooling.
See also
Overlay plan
References
^ Haar, Dan and Vanessa Hua. "Regulators Have Area Code Plan". The Courant. August 18, 1999. Accessed October 28, 2005.
- - NANPA : Number Resources - NPA (Area) Codes
^ - c - Madison, Linc. "LincMad's Area Code Locator Table". LincMad. September 29, 2005. Accessed October 28, 2005.
- ^ - Utah Division of Public Utilities
- ^ - NANPA PL-269
- - nanpa.com/reports/NPA_Relief_Activity_Status_Report_110107.pdf
- - Area Codes in Southeast Pennsylvania
References from: List_of_area_code_overlays Wiki
overlay US 2018