A system for authenticating client devices for communication with one or more wireless communications networks, includes a client device configured to receive a client-side global time from a time tracking system and generate a response to an authentication challenge based on the authentication challenge, the client-side global time, a client device identifier associated with the client device, and optionally location data that corresponds to a location of the client device. The system further includes a security gateway configured to receive a gateway-side global time from the time tracking system, generate an expected response to the authentication challenge based on the authentication challenge, the gateway-side global time, the client device identifier, and optionally location data that corresponds to an expected location of the client device, receive the response to the authentication challenge, and authenticate the client device on a wireless communications network based on the response and the expected response.