Digital Subscriber Line, or DSL, is a family of technologies that provide digital data transmission over the wires used in the "last mile" of a local telephone network. Typically, the download speed of DSL ranges from 128 kilobits per second (kbit/s) to 24,000 kbit/s depending on DSL technology and service level implemented. Upload speed is lower than download speed for Asymmetric Digital Subscriber Line (ADSL) and equal to download speed for Symmetric Digital Subscriber Line (SDSL). All DSL is half duplex, which can make DSL less suitable than fully bi-directional alternatives for applications, like telephony, that are time sensitive and require simultaneous bi-directional communication.
