This project is used as an electronic private exchange. It has two telephones, which have the intercom facility, and they can be connected to the telephone line. All the functions are controlled by the 8-bit microcontroller AT89C2051 which has an Pro

Introduction Dial your number using DTMF phone or Cell phone from anywhere in the world and remotely turn on/off any of the 8 relays. The MCU on the interface senses Telephone ring, Automatic telephone pick up, and line hang up, displays informati