In-line filter for phones or telephone equipment sharing a two-line phone jack. Isolates DSL and home phoneline networking (HPN) signals from voice signal on both lines for peak data performance and voice quality. Effectively filters one or more phone devices (standard or cordless phone, answering machine, dial-up modem, fax machine, etc.) on line 1 and line 2. Use one filter at each phone jack in use in the home or office. Easy to install—just plug the filter cord into any standard phone jack, and plug the phone cord into the filter. Provides one unfiltered jack for DSL/HPN plus one filtered jack for any single or two-line phone device.