An IntereXchange Carrier (IXC) is a U.S. legal and regulatory term for a telecommunicationsTelecommunication is the transmission of signals over a distance for the purpose of communication. In modern times, this process typically involves the sending of electromagnetic waves by electronic transmitters, but in earlier times telecommunication may have involved the use of smoke signals, drums or semaphore. Today, telecommunication is widespread and devices that assist the process, such as the television, ...telecommunications company, commonly called a long-distance telephone company, such as AT&TAT&T Inc. is the largest provider of both local and long distance telephone services, wireless service, and DSL Internet access in the United States. The current AT&T, which is based in San Antonio, Texas, United States, is the rechristened SBC Communications, following the purchase of "Ma Bell", AT&T Corporation. As a part ...AT&T, MCIMCI, Inc. was an American telecommunications company that was headquartered in Ashburn, Virginia. The corporation was the result of the merger of WorldCom (formerly known as LDDS followed by LDDS WorldCom) and MCI Communications, and used the name MCI WorldCom followed by WorldCom before taking its final name on April 14, 2003 as part of the corporation's emergence from ...MCI and SprintSprint Nextel Corporation is one of the largest telecommunications companies in the world. With 55 million subscribers, Sprint Nextel operates the third largest wireless telecommunications network in the United States (based on total wireless customers), behind Verizon Wireless and AT&T. Sprint is ...Sprint in the United States. It is defined as carriers which provide inter local access and transport areaLocal access and transport area (LATA) is a term used in U.S. telecommunications regulation. It represents a geographical area of the United States under the terms of the Modification of Final Judgment (MFJ) that precipitated the breakup of the original AT&T into the "Baby Bells" or created since that time for wireline regulation. Generally, a LATA represents an area within which a divested Regional Bell operating company (RBOC) is permitted to offer exchange ...local access and transport area (LATA) communication.

An IXC carries traffic, usually voice traffic between telephone exchangesIn the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make phone calls "work" in the sense of making connections and relaying the speech ...telephone exchanges. Telephone exchanges are usually identified in the United States by the three-digit area code and the first three digits of the phone number. Different exchanges are generally in different geographic locations, such as separate central officesIn the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make phone calls "work" in the sense of making connections and relaying ...central offices (COs, also called "wire centers").

IXCs used to carry voice traffic on analog linesIn telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. Each circuit that is dedicated cannot be used by other callers until the circuit is released and a new connection is set up. Even if no actual communication is taking place in a dedicated circuit then, that channel still remains unavailable to other users. Channels that are available for new calls to be set up are said to be idle. For call setup and control (and other administrative ...voice traffic on analog lines, but these days, most voice traffic is digitized. Therefore, voice traffic is more typically a data stream. These voice data streams therefore can be intermixed with data traffic too, such as uplinks for DSLDSL or xDSL, is a family of technologies that provide digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop, although in recent years, many have adopted digital subscriber line as a more marketing-friendly term for the most popular version of consumer-ready DSL, ADSL. Typically, the download speed of consumer DSL services ranges from 256 kilobits per second (kbit/s) ...DSL. Most commonly, links to and from COs are ATMAsynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ATM provides data link layer services that run over SONET (Synchronous Optical Networking) Layer 1 links. This differs from other technologies based on packet-switched ...ATM links carried on optical fiberAn optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. In fibers with large core diameter, the confinement is based on total internal reflection. In smaller diameter core fibers, (widely used for most communication links longer than 200 meters) the confinement relies on establishing a waveguide. Fiber optics ...optical fiber.