GSM has cryptographic challenge-response authentication, but only handset authenticates itself to the network, not the other way around. Also, network can just

GSM has cryptographic challenge-response authentication, but only handset authenticates itself to the network, not the other way around. Also, network can just not require authentication at all (which is how devices like this work). Having authentication credentials preloaded is impractical for both GSM and UMTS/W-CDMA, as authentication uses secret shared key that is (should be) unique to each customer.