high-bitrate DSL

High-bit-rate DSL (HDSL) is a networking technology that provides high-speed Internet connections over traditional telephone lines. Developed around 1990, HDSL uses technology similar to ISDN to transmit data at speeds up to 1.544 Mbps over two twisted-pair lines. Unlike later asymmetric DSL (ADSL) technologies, HDSL is symmetric, meaning the upstream and downstream data rates are the same. HDSL was initially intended for on-demand television but was later repurposed for Internet access. While effective, DSL technology is limited by distance, requiring users to be within a few miles of a telephone switching office, and its speeds are generally slower than cable and fiber-optic services.1