A security system implemented with a communication device includes a remote communication device, a local communication device, a main controller and at least one main sensor. The remote communication device and local communication device are connected via communication connection. Each main sensor detects status of a monitoring location. When each main sensor is triggered, each main sensor sends an output signal to the main controller. The main controller collects and processes each output signal, and transmits the processed output signals to the local communication device. The local communication device transforms receives output signals into a text warning message. The text warning message transmits to remote communication device via Short Message Service whereby a user is informed of the status occurred in a remote monitoring location.