An access technology that allows voice and high-speed data to be sent simultaneously over local exchange service copper facilities; the technology supports data rates of up to 1. 544 Mb/s when receiving data (downstream rate) and up to 256 kb/s when sending data (upstream rate. ) 2. A modem technology that provides enhanced and affordable access to the Internet, live video, and a wide variety of other multimedia broadband services over existing copper twisted-pair wirelines; usually the ADSL operates with different data rates in the two directions.