This paper deals with the design and implementation of a system kit which allow the easy use of a mobile phone to control the devices with security. A user can send DTMF tone to the control unit using any GSM mobile phone from anywhere in the world. To access the control unit, the user should send an authentication code (DTMF) along with the desired command to perform on the devices. A mobile phone attached to the microcontroller which can answer automatically works as the DTMF receiver. PIC16F628A microcontroller is programmed and it can control (ON/OFF) eight devices. In addition, we have implemented the DTMF decoder within the microcontroller using an algorithm (Goertzel algorithm). Upon being properly authenticated, the ON/OFF of different devices can be carried out by the microcontroller according to users own accord. The proposed work has been done and verified in real time.