“Carrier A company that provides communications circuits. Carriers are either “private” or “common.” A “private” carrier can refuse service. A “common” carrier cannot. Most of the carriers in our industry (the local phone company, AT&T, MCI WorldCom, US, Sprint, etc.) are common carriers. cf. Service Provider exchanges. (2) A long-distance telephone company offering circuit-switched, leased-line or packet-switched service or some combination thereof.”