DSL Filter +
A DSL filter is an analog low-pass filter installed between analog devices (such as telephones or analog modems) and a plain old telephone service (POTS) line, in order to prevent interference between such devices and a digital subscriber line (DSL) service operating on the same line. Without DSL filters, signals or echoes from analog devices at the top of their frequency range can result in reduced performance and connection problems with DSL service, while those from the DSL service at the bottom of its range can result in line noise and other issues for analog devices.