A long-distance telephone company such as AT&T, MCI, or Sprint.
Common carrier providing communications channels between local telephone companies (LECs or local exchange carriers). Also known as long distance carriers, such as AT&T, MCI, Sprint, WilTel, etc.
Very much a US term, an IXC is a long distance telecommunications provider that offers a range of circuit-switched, packet-switched, leased line, and enhanced communications services; any company that provides communications services between exchanges on a long haul basis. In Europe, Asia, and other nations around the world, the local telco also serves as the major IXC in the country. See Telco.