The Free On-line Dictionary of Computing (30 December 2018):

local exchange carrier

    (LEC) A company allowed to handle local calls
   following the break-up of the Bell system in the US by
   anti-trust regulators.  These vary from Regional Bell
   Operating Companies (RBOC) through to small independents such
   as Farmers Cooperative.

   Local exchange carriers are not allowed to handle
   long-distance traffic.  This is handled by inter-exchange
   carriers (IXC) who are not allowed to handle local calls.

   (2002-08-28)