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Handbook for Arkansas, Kansas, Missouri, Oklahoma, Texas

Service Areas and Area Code Splits/Overlays

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Area Code Splits & Service Areas     


Important: All information concerning area code splits is applicable to both facilities-based CLECs and CLEC-Resellers. In this section of the CLEC Handbook, the term 'CLEC' is used to indicate both facilities-based CLECs and CLEC-Resellers.      

All Area Code splits:      

  • Take place on weekends (starting Saturday).

  • Require that any internal tables or files that are NPA-NXX sensitive be changed.

  • Require the CLECs to do their conversions of tables, files, etc. associated with the area code split the weekend of the split.

  • Require that systems normally used by the Local Service Center (LSC) and/or the CLECs be turned down, in order to modify tables, files, etc. associated with the area code split. This turn down usually occurs at the close of business on the Friday prior to the split. Because of this turn down, the LSC does not accept orders over the weekend of the split.

  • Require no turn down of the Automated Location Identifier (ALI) retrieval system for E9-1-1. Conversion of this system takes place during regularly scheduled maintenance.

  • Require that all trouble reports in the areas impacted by the split be manually processed during the time that the systems are turned down.

Note: Calls within an area code which were considered 'local' prior to the split will continue to be local after the split, even if they are between two area codes.

Permissive Dialing Period      

A permissive dialing period is scheduled to begin the first day after the area code split occurs and end six months later. During this period:      

  • Calls across the new area code split will be permitted by dialing either seven digits (7D), or ten digits (10D).

  • Calls to the new NPA from outside the present NPA will be permitted when either the old or new NPA is dialed.

  • Local calls dialed on a 7D basis prior to the start of the permissive dialing period, but now dialed on a 10D basis between the old and new NPAs, will remain local calls.


Conversions of Area Codes on Pending Service Orders      

Southwestern Bell (SWBT) performs NPA conversions on all pending service orders for prefixes (NXXs) whose NPA is changing.      

  • A request is considered eligible for conversion (and will be completed with the area code changed) if the current version of the request, at the time of the area code conversion, has not been rejected, canceled, or completed.

  • If a record is sent prior to conversion, the requests are converted and sent with the new area code.

  • The last batch of requests received in the LSC prior to the conversion is at 5:00 P.M. the Friday before the conversion. All batches received before this time are converted and processed.

  • All new requests and service orders should have the new area code.

  • Sixty days following a split, orders will not be accepted with the old area code on prefixes which have become part of the new area code.

Preparing Computer for Split      

Certain SWBT systems will require turn down during the area code split weekend. The impact of this turn down to CLECs is as follows:      

  • Turn down of the computer systems used by SWBT (LSC and others) and/or the CLECs will take place at 5:30 P.M. on the Friday before the area code split. These systems will not be available for use until 6:00 A.M. on the Monday following the area code split.

  • Last inbound transmission (of new requests and supplementals from the CLECs) are those received at 5:00 P.M. on Friday before the area code split. This last batch will be converted to the new area code prior to processing.

  • Last outbound transmissions (e.g., of processing response screens) will be made at 5:00 P.M. on the Friday prior to the split.

Service Areas, Area Code Splits and Overlays      

  • Telephone Service areas are identified via Local Access Transport Areas (LATAs). 
  • Each LATA includes one or more three-digit Number Plan Area (NPA) codes or area codes. 
  • Periodically, new NPA codes are needed when the current demand for telephone numbers in an NPA grows too large.  At these times, it becomes necessary to split an NPA and to assign certain prefixes (NXXs) to a new NPA. 
  • In addition to area code splits, new NPA ranges can be created via an area code overlay, whereby a new area code is added to a geographic area.

To obtain area code information for the entire North American Numbering Plan, see the NANPA external website at NPA Relief Planning, Area Code Maps, LATA information, etc. can be found on this site.  Additional information on splits and overlays may also be found by using the Accessible Letter search.

Note: Links to external Internet sites are provided as a convenience to users. Southwestern Bell, Pacific Bell, Nevada Bell, SNET, Ameritech and its affiliates are not responsible for the content of these external sites. The listing of an external site does not imply endorsement of the site by AT&T or its subsidiaries.