The D-Link DSL-16MF Microfilter separates the analogue voice-frequency signals from the DSL (Broadband) data signals. If microfilters are not used, the DSL data signals are heard as “noise” on any equipment connected to the telephone line.
Apart from being disruptive during a telephone conversation, there is the possibility that the additional DSL signals may cause interference with alarm units that may be connected across the line.