This is schematic and Gerber files of PCB that is used for GSM alarm system. This is industrial-grade system with many features like 1-wire (iButton) interface, additional interface for video camera (UART JPEG camera is used), SD card to store pictures from camera and send them by GSM to remote mobile phone. Can be used as a reference design for anyone who wants to make own GSM alarm system system based on SIM300C module from Simcom.