Incumbent local exchange carrier
An incumbent local exchange carrier (ILEC) is a local telephone company which held the regional monopoly on landline service before the market was opened to competitive local exchange carriers, or the corporate successor of such a firm, in the United States and Canada. == Definition == An incumbent local exchange carrier is a local exchange carrier (LEC) in a specific area that on the date of enactment of the Telecommunications Act of 1996, provided telephone exchange service on the date of enactment, was deemed to be a member of the National Exchange Carrier Association pursuant to the Code of Federal Regulations (C.F.R) Title 47, section 69.601(b).
Source: Wikipedia — Incumbent local exchange carrier (CC BY-SA 4.0)