This document describes a smart home security system that uses wireless sensor networks and GSM technology. The system can detect theft, gas leaks, temperature changes and send alarm messages to a mobile phone. It allows users to control home appliances like fans and lights remotely. The system uses low-cost and commonly available components like cell phones, SIM cards, and GSM modems. Sensors for smoke, LPG, temperature, and motion can trigger alarm messages. The system has applications for home, locker, industrial and bank security.