[2] With asynchronous digital subscriber line (ADSL) technology, voice and data traffic are carried simultaneously and independently over existing copper subscriber loops. Unlike the integrated services digital network, which transports both voice and data in digital form--and does not work with legacy telephones--under ADSL, plain old telephone service (POTS) is provided in the traditional way. For best reliability, the analog voice traffic is kept separate from the digital data by a passive filter known as a POTS splitter. At the central office, the digital traffic is directed to Internet routers, broadcast feeds, and so on, thereby offloading the POTS switch.