GSM architecture : Network Subsystem (NSS) (3/6)

GSM architecture : Network Subsystem (NSS)

One of these registers is the Visitor Location Register (VLR), which is usually to be found in
the MSC, but is a functional unit in its own right. It is designed as a dynamic subscriber file
with dedicated geographical areas of responsibility, the so-called Location Areas. The VLR
acquires the data of all GSM customers in its areas and is always well informed of their
whereabouts. It assists the MSC in the acquisition of charge-relevant data with subscriber
information. The bills are prepared from these data in the Billing Center. But where does the
VLR get the GSM customer data from?