Vellman remote telephone switchThis kit makes it possible to turn up to three devices on or off over the telephone. It is also possible to check the condition of a switch (open or closed). Example : when you are away on holiday, you may switch the lights on and off from time to time, check the alarm or turn on the heating before returning home. A major advantage of this circuit lies in the fact that audio signals are used to tell whether a specific output has been turned on or off. Operation is protected by a user defined code, which is simply keyed in from the telephone keypad
This device can switch up to 3 relays. Really simple to install and use. I used to control a remote central heating to turn on / off so house correct temperature when home but not waste entery when away. It has 3 relays so you can control other things.
it is operated by the phone key pad tones, although I have not tried I assume a simple DTMF tone generator the old banking systems would work too.
Any questions please ask.