GSM architecture : Network Subsystem (NSS) (5/6)

GSM architecture : Network Subsystem (NSS)

The Authentication Center (AuC) contains the customer data necessary to protect
connections against unauthorised access, and is mostly integral to the HLR. The AUC
checks the information stored in the Subscriber Identity Module, that is the SIM card, for
correspondence with its own register. If the data proves to be identical, the authentication of
the subscriber is successful, and he is given permission to enter the network. If the SIM card
is stolen, authorisation to access the network is disabled very easily via the AUC.
Additionally, the AUC provides necessary information to cipher the air interface.