Network switching subsystem#Visitor location register .28VLR.29

The Visitor Location Register (VLR ) ( German: Visitor Location Register ) is a term from the mobile technology. The VLR is a database in the mobile services switching center (MSC). Here is the information about all participants are stored, the just are in the catchment area of the MSC.

VLR data

In the VLR database contains the following information about each logged onto mobile device

The information in the VLR are a copy of the subscriber data that are located in the Home Location Register (HLR ).

Call set-up

The phone number of a mobile subscriber does not contain any information about his whereabouts. Radio cell in which he is currently registered, Location Register may be obtained only through a request from the HLR and Visitor. As a basis for such a request is a protocol based on Signaling System 7. From the information of the response, a corresponding call setup is performed.

If a telephone call to the mobile terminal are mediated, the HLR is determined by the subscriber's number, in which the master data of the participant are. The HLR returns the MSC address is in the VLR of the subscriber is currently registered. On the basis of this MSC VLR data, the location area of the subscriber is determined. In all radio cells belonging to this location area (LA), then a paging signal is transmitted via the signaling channel containing the TMSI.

Location Update

Moves a mobile phone in the radio cell to another location area or passes a predetermined time from the mobile operators without mobile phone is connected to the network, is carried out by the terminal, a location update. Is this the catchment area of the MSC is registered in the VLR of the participants, do not leave, only the location area information is updated in the VLR.

The subscriber changes in the catchment area of another MSC, the new MSC sends the new location area of the subscriber associated HLR, which then deletes the data in the VLR of the old MSC and the current subscriber record sends to the VLR of the new MSC.