A carrier network is the proprietary network infrastructure belonging to a telecommunications service provider such as Verizon, AT&T or Sprint. Telecom carriers are authorized by regulatory agencies to operate telecommunications systems. Carrier networks are made up of large, complex configurations of hardware, interconnected to provide communications services to people spread over large geographic areas.
Specific device types served by a carrier network include telephony equipment, CATV (community access television) receivers, satellite television receivers, mobile computing devices, PCs (personal computers), and certain specialized items such as medical and surveillance equipment.
Carrier networks distribute massive quantities of data over great distances. The long-distance signal-conveying medium in a carrier network is sometimes called the backbone. Most of the backbone is built around fiber optics, although some portions of some networks still employ "copper" (cable). Internet service to individual end users can take place through fiber optics (in the best-case scenario) although cable, wireless, and satellite Internet modes are more common. In rural areas, some end users rely on twisted pair telephone lines for their Internet access.