lol, i have a rc car that runs off dtmf , the ic i used plugged in to headphone jack of "receiver cell phone " and outputs dtmf to 4-bit parallel, so it needed a cell phone & sim card to receive, and any other type of tone phone for transmit
how do you plan to connect phone to circuit?
do you have the circuits already?
.... that is the first step....before thinking about code
1)hook up relay circuit to pic * 8pins
2)hook up dtmf decoder to pic * 4pins + 4 more for ack and such
3) learn to switch relays
4) learn to read parallel bus & handshake with dtmf chip
5) bind the 2