Methods and systems are provided for power management and security for wireless modules in “Machine-to-Machine” communications. A wireless module operating in a wireless network and with access to the Internet can efficiently and securely communicate with a server. The wireless network can be a public land mobile network (PLMN) that supports wireless wide area network technology including 3rd generation (3G) and 4th generation (4G) networks, and future generations as well. The wireless module can (i) utilize sleep and active states to monitor a monitored unit with a sensor and (ii) communicate with wireless network by utilizing a radio. The wireless module can include power control steps to reduce the energy consumed after sending sensor data by minimizing a tail period of a radio resource control (RRC) connected state. Messages between the wireless module and server can be transmitted according to the UDP or UDP Lite protocol with channel coding in the datagram body for efficiency while providing robustness to bit errors. The wireless module and server can utilize public key infrastructure (PKI) such as public keys to encrypt messages. The wireless module and server can use private keys to generate digital signatures for datagrams sent and decrypt messages received. The communication system between the wireless module and the server can conserve battery life in the wireless module while providing a system that is secure, scalable, and robust.