There are two ways to accomplish this.
One: Put a filter on every phone and phone like device in the house. Phone, Fax, answering machine, etc. And the DSL line remains unfiltered. The phone companies like this for self install kits because you dont have to open up your side of the NID box outside and screw with it. If the jack doesn't have a phone or anything else plugged in, no need to put a filter on it.
Two: Put a splitter in the NID phone box outside which splits up phone and voice before it gets into your house. This requires some way to make sure the DSL split part gets to the DSL phone plug. Generally by using a spare pair of wires on the phone cables in your house, or by running a totally separate cable run. This used to be done often with DSL installs, but since the popularity of self install kits has mostly gone by the wayside. This method is also best in terms of possible loss of DSL speed. Filters can affect DSL speed, so can the extra phone wire length since DSL is greatly dependant on distance from CO or RT. Since the splitter needs a dedicated wire to the DSL jack, its essentially a home run as well.
For a year or two I had been using the DSL phone filters in my house. Then I put a splitter and setup a home run (dedicated connection to DSL) at my house to try and sqeeze every possible last bit of speed out of my connection.