ADSL Plug Splitter/Microfilter for use at each phone socket around your house.
What is the difference between a passive and an active Microfilter? A passive Microfilter does not actively filter and only does so when a signal is being sent down the line, active Microfilters have more circuitry and filter all the time. Active Microfilters tend to be more expensive and allow for more devices to be connected at any one time. The only BT approved Microfilters are active filters