In the United States, wireline telephone companies are divided into two large categories: long-distance (interexchange carrier, or IXCs) and local (local exchange carrier, or LECs).
This structure is a result of 1984 divestiture of then-regulated monopoly carrier American Telephone & Telegraph.
The divestiture created local exchange carriers for the management of local telephone lines and switches, and provisioning of local phone services within their business area, as well as the long-distance calls originating or terminating in their business area.
The vast majority of the United States are served by LECs called Baby Bells, or RBOCs (Regional Bell Operating Companies).
The rest of the United States, most commonly in rural or outlying suburban areas, are served by independent LECs, known in the industry simply as the "independents."
Although independent companies typically serve these areas, RBOC LECs still have vast territories of low population density regions of the country.
Therefore, independents generally exist as pockets of territory within a greater RBOC region.
Local calls are defined as calls originating and terminating within a local access and transport area (LATA) which is defined by the Federal Communications Commission.
All of the Baby Bells, as well as other LECs, typically operate businesses in more than one LATA yet their services of local telephone calls are still defined by LATA boundaries, not their business areas.
The following information applied to residential local telephone service in the Detroit, Michigan area during the 1970s and 1980s.
Residential local exchange carrier services typically charges
Generally, the local exchange carrier has the following duties: