When the ADSL and PSTN works on the same line at the same time, a problem the electronics in a normal telephone for high frequency signals ADSL: ADSL signals can be reduced (with high capacity intercom can be resonances in the phone, impedance mismatch ) and ADSL signals can be heard as the sound on some phones (electronic phone demodulates RF signal is out of range voting frequency noise). Just to keep these systems and stop interfering with each other, it is necessary for the two components of the telephone in your home to separate. This is where the filter / splitter comes in. The ADSL POTS splitter / filter allows you to take full advantage of the frequency 1.1 MHz copper line to take, stopping the ADSL and phone systems interfere with each others. An ADSL filter is normally a small plastic box with a short cable that connects to your telephone jack and two outputs, one for your ADSL modem and a telephone. Some filters have an exit by calling them. ADSL filter to the frequency band for each of the outlets, telephone or ADSL to select just the right tire and sending in the socket. The output of the phone is not receiving phone frequencies (from DC to 3.4 kHz) and the output is higher and ADSL freuquencies (above 25 kHz). For good system performance, it is very important that all your other phone equipment is separated from the ADSL signals using a splitter / filter – This equipment includes telephones, answering machines, “normal” modems, etc., etc. .