AT&T Clec Online

Handbook for California and Nevada

Service Area-Area Code Information

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Service Areas

  • Telephone service areas are identified via Local Access Transport Areas (LATAs). 
  • Each LATA includes one or more three-digit Numbering 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.

Refer to the NANPAwebsite for area code information. 


Area Code Split Overview

Important:   All information concerning area code splits is applicable to both facilities-based CLECs and CLEC-Resellers and 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 CLEC 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 CLEC 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.     
  • The Automated Location Identifier (ALI) retrieval system, for E911, does not require a turn down.   Conversion of this system takes place during regularly scheduled maintenance.    
  • Requires 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.    

Preparing Computers for Split

Certain AT&T 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 AT&T (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 supplemental 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.

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

AT&T 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.     
  • There is a 60-day period during which the LSC allows for requests made using the old area code. The area code will be converted on these requests.