Zoom Telephonics

This inline Filter/Splitter plugs into a wall jack, and provides separate ports for filtered voice (POTS) and high-speed ADSL data signals.

The Filter/Splitter has two jacks: one (unfiltered) for a DSL modem and another (filtered) for a voice-grade device (phone, fax, answering machine, etc.) It keeps the voice-grade devices from interfering with the performance of the DSL modem, and keeps noise from the data signal off the voice devices.