To allow devices to authenticate to a wide area mobile network when they temporarily do not have a connection to a SIM card and to authenticate the base station and so protect against false base stations, a system is provided where certain authentication credentials are pre-fetched while connection to the SIM card and the authentication subsystem of the wide area mobile network are in signaling connection. These advance credentials are then presented by the devices in authentication requests without requiring access via the mobile network or the connected presence of the SIM card being necessary for successful authentication.