That answer to this question is maybe. It usually depends on your local telephone company and DSL technology.

In the majority of circumstances, the answer is "no"; A single phone line is all that is required (i.e. line-sharing). ADSL operates at a different set of frequencies than standard voice telephones. The difference in frequencies allows both voice traffic and IP (internet) traffic to co-exist on the same physical phone line. You simply need to obtain line filters (usually provided by your chosen service as part of your setup package) to plug in to the wall jacks you wish to use for normal voice telephones.

Unfortunatly, in a few areas with different types of DSL (such as SDSL), the answer may be yes.