How Do DSL Filters Work?

DSL filters don't let the DSL signals through into the phone lines in your house. Called "low pass" filters, they only let lower signals at the voice frequency into your phones. You just need resistors, capacitors and coils to build one. If you put a filter on everything except your DSL modem, you'll be ready to go.

You can put an inline filter on every phone and machine other than the DSL modem that connects to your phone jack. You can also put one filter where the phone line enters your house and then split off a separate line that goes right to the DSL modem, because it needs the full signal.

The first solution in the prior section is called a set of filters. The second is called the splitter. There really isn't much difference, except that with a splitter system you don't need nearly as many filters. You just run your DSL modem line straight to it from the phone input while blocking the high-spectrum signal everywhere else in the house, which is the same thing that a set of small filters on each device would do.

Many manufacturers produce DSL filters, so you have several options. If you need signal splitting, surge protection or other features with your filter, look for that as an option. If you're buying filters for each device, consider which devices you'll be using while you're on the Internet, and only buy filters that you need.