Wireless router is a modem - you connect the wireless router to the telephone socket.
My house telephone and wireless router both connect to a filter, mine is marked BT ADSL MF50.
Filter has 3" lead that plugs into telephone socket.
All seven computers in the house are wireless enabled and are able to self-discover our own router and those of four neighbours too. Op sys in use are XP Vista and Mac.
Peccavi, November 2008