A telco service for transmitting data using line drivers. Local Area Data Channel (LADC), also called telco restricted lines, conforms to the Bell 43401 standard published by AT&T. The LADC standard specifies “dc continuity,” which basically means that metallic (copper) conductors (usually the unshielded twisted-pair cabling used for phone lines) must be used.
LADC lines must also be unloaded - that is, without terminators, loading coils, or protection circuitry that can add to the inductance of the line and thus distort signals. LADC lines are available to distances of 5 kilometers from the telco’s central office (CO); the longer the distance, the lower the bandwidth supported.