I successfully completed this project under my COP course this semester.
The project deals with the programming of PIC 16F84A so that it could be used in the circuit to control relays using telephone. Also the hardware implementation is done to make it a proper working circuit.
Once the PIC is programmed and is connected to the circuit, we can actually control the appliances by just giving certain number of rings on telephone to which it is attached. Its like a universal remoter control, and you can control appliances or any other circuit from anywhere in the world !
Note : It required 16F84A microcontroller, MCT2E optocoupler, NE555 timer, 7805C regulator IC, some resistors, capacitors, transistors, crystal (4MH0z), DIP Switch, relays and diodes.