DTMF is a method of representing digits with tone frequencies, in order to transmit then over an analog communications network. Here DTMF can be used to control electronics appliances remotely using our mobile handset or fixed landline .In this circuit main components are dtmf decoder, demultiplexer and relay driver circuit. Its typical applications are security system and control almost every electronics devices from anywhere in the world by using mobile communication network. This Mobile Switching Device Using DTMF Project was done in Electronics and Communication Engineering.