A data modem that uses the bandwidth of a given cable system, which promise speeds of up to 80 times faster than an ISDN line or six times faster than a dedicated T1 line (the type of connection most large corporations use). Because cable modems provide Internet access over cable TV networks (which rely primarily on fiber optic or coaxial cable), they are much faster than modems that use phone lines. Bandwidths are typically up to 30 Mbps in the downstream direction.