Local access and transport area
Local access and transport area (LATA) is a term used in U.S. telecommunications regulation. It represents a geographical area of the United States under the terms of the Modification of Final Judgment (MFJ) entered by the United States District Court for the District of Columbia in Civil Action number 82-0192 or any other geographic area designated as a LATA in the National Exchange Carrier Association, Inc. Tariff FCC No. 4. that precipitated the breakup of the original AT&T into the "Baby Bells" or created since that time for wireline regulation. Generally, a LATA represents  an area within which a divested Regional Bell Operating Company (RBOC) is permitted to offer exchange telecommunications and exchange access services. Under the terms of the MFJ, the RBOCs are generally prohibited from providing services that originate in one LATA and terminate in another. LATA boundaries tend to be drawn around markets, and not necessarily along existing state or area code borders. Some LATAs cross over state boundaries, such as those for the New York metropolitan area and Greenwich, Connecticut; Chicago, Illinois; Portland, Oregon; and areas between Maryland, Virginia, and West Virginia. Area codes and LATAs do not necessarily share  boundaries; many LATAs exist in multiple area codes, and many area codes exist in multiple LATAs. Originally, the LATAs were grouped into regions within which one particular RBOC was allowed to provide services. The LATAs in each of these regions are numbered beginning with the same digit. Generally, the LATAs were associated with carriers or other indications in the following manner: In addition to this list, two local carriers were made independent: Cincinnati Bell in the Cincinnati area, and SNET (a former unit of AT&T, sold to Frontier) in Connecticut. These were assigned LATAs in the 9xx range. Since the  breakup of the original AT&T in 1984, however, some amount of deregulation, as well as a number of phone company mergers, have blurred the significance of these regions. A number of new LATAs have been formed within these regions since their inception, most beginning with the digit 9. LATAs contribute to an often confusing aspect of long–distance telephone service. Due to the various and overlapping regulatory limitations and inter-business arrangements, phone companies typically provide differing types of “long distance” service, each with potentially different rates: Given the complexity of the legal and financial issues involved in each distinction , many long-distance companies tend to not explain the details of these different rates, which can lead to billing questions from surprised customers. Local carriers have various alternative terms for LATAs such as “Service Area” by Pacific Bell in California, or “Regional Calling Area” by Verizon in Maryland. In order to facilitate the sharing of Telcordia telephone routing databases between countries, LATAs were later defined for the provinces of Canada, the other countries and territories of the North American Numbering Plan, and Mexico. Aside from U.S. territories, LATAs have no regulatory purpose in these areas. In 2000, the Canadian Radio -television and Telecommunications Commission eliminated all Canadian provincial LATAs in favor of a single LATA for Canada (888). No LATAs exist with a second digit of 0 or 1, which distinguished them from traditional area codes. List of LATAs. US state LATAs. The city or place name given with some LATAs is the name given to identify the LATA, not the limit of its boundary. Generally this is the most significant metropolitan area in the LATA. In some cases, a LATA is named after the largest phone exchange in the LATA that was historically served by an RBOC. For example , the largest city in the Pahrump LATA in Nevada is Las Vegas. Since Las Vegas was not historically served by an RBOC, the LATA is named after the smaller town of Pahrump, which was historically served by Nevada Bell (now AT&T Inc.). Also, listing under a state does not necessarily limit the LATA's territory to that state; there may be overlaps as well as enclaves. Areas that include notable portions of other states are explained, but not all LATA state overlaps may be detailed. LATA boundaries are not always solidly defined. Inter-carrier agreements, change proposals to the Federal  Communications Commission (FCC), and new wiring developments into rural areas can and do often alter the effective borders between LATAs. Many sources on LATA boundary information conflict with each other at detailed levels. Telcordia data may provide the most up-to-date details of LATA inclusions. Canada. As LATAs exist for US regulatory purposes, where they serve as a demarcation between intra-LATA calls (handled by regional Bell operating companies) and inter-LATA calls (handled by interstate long-distance carriers such as AT&T), they have no legal significance in Canada. As of 2000, all of Canada (except for non-geographic  numbers) is identified as LATA 888. The use of this LATA set to identify individual provinces is therefore deprecated: Local interconnection region. Canada does define local interconnection regions (LIR's), which determine where points of interconnection (POI) must be provided by competing local exchange and mobile carriers to provide local number portability. A Canadian LIR is geographically smaller than a US LATA, typically comparable in size to a small city's flat-rate local calling area or to an entire large regional municipality. In areas where a small-city Digital Multiplex System controls a group of remote switching centres, one  for each surrounding village, the local interconnect region normally includes each exchange in the city plus all downstream remotes of those exchanges. In a Toronto-sized city, the LIR will include only the city itself. While the LIRs resemble local calling areas in geographic size, there are some key differences: One example: The tiny unincorporated village of Beebe Plain, divided by the Quebec-Vermont border, is served by +1-819-876 Rock Island, Quebec, Canada (a remote station controlled from Magog) and +1-802-873 Derby Line, Vermont, USA (a remote station controlled from St. Johnsbury). Magog and St. Johnsbury  are both a long-distance call from anywhere in Beebe Plain, even though Canadian subscribers can place local calls to Sherbrooke, US subscribers can locally call Newport and an international call within the village is local. An LIR assignment which follows network topology places the Canadian remote station in Magog's LIR, not Sherbrooke's LIR.