I needed to connect two separate phones on the telephone out of the box ADSL (wired and wireless). But I feared interference but I gave it a shot. It is a success: incoming calls are sent on both machines plugged into the RJ11 outputs of the filter. Stations ring simultaneously and you can answer the call either on one and the other. No problem either on outgoing calls on both machines (not simultaneously of course!): Positions are reactive to one another in use, no conflict. As for my case, this is perfectly satisfactory.
