You need

1) A ring detector circuit which will detect the presence of ringing signal on telephone line.

2) Some sort of line seize mechanism, which will be used to answer the incoming call. This may be a dummy resistive load.

3) Some sort of authentication so that your micro knows that it is a call for remote control application, and not a normal telephone call.

4) A DAA circuit which will be used to interface the DTMF receiver chip to telephone line.

Thats all about hardware. Be sure to get the specifications of your telephone line before you design/select any component/circuit.

Also permission/type approval may be necessary before you connect your gadget to telephone line.