GSM architecture : Network Subsystem (NSS) (4/6)

GSM architecture : Network Subsystem (NSS)

For GSM customer data acquisition, there is a register, the so-called Home Location Register
(HLR), in which each network operator registers the customer data necessary for dealing
with traffic. The HLR supplies these data to all VLRs in which the GSM customers involved
are to be found at any given moment. Inversely, the VLR in question informs the HLR of the
location area of the customer, and is thus able to give routing information when calls come
in. The HLR data contain information on access rights with regard to roaming, service rights
with regard to voice, fax and data services, and additional subscribed services.