This diagram is the schematic diagram of telephone switcher using relays. This device connects to the telephone line and can be used to remotely control up to 4 relay outputs using a DTMF (tone dialing) telephone. A number of user settings are available to improve the useability and security of the device. The kit comes complete with a small plastic case with silk-screened front and rear panels.
The brain of this circuit is microcontroller chip Atmel MCS51 family AT89C2051. The source code is not available here, you may find out the source code by yourself.
The diagram is quite hard to designed in PCB, you may purchase the telephone switcher kits from this page:† http://electronickits.com/kit/complete/tele/ck603.htm
The application notes for this circuit can be download here