Abstract: A method of authenticating a device for secure communications between the device and a server comprises transmitting a security token request via a data communications network using a data communications protocol. A message is received from the device that no security token is available. In response, an identification request is transmitted from the server to the device via the data communications network and an identification message is received from the device via a mobile communications network using a mobile communications protocol, the identification message including an identification of the device. The identification of the device is stored in a memory. A security token is generated and transmitted to the device via the data communications network. The security token is stored associated with the identification of the device in a memory connected to the server for use in future secure communications with the device via the data communications network.