What's the difference between HLR and VLR?

Home Location Registry(HLR) registers and maintains permanent information of the subscriber while Visitor Location Registry(VLR) is a temporary registry of the subscriber information when the subcriber moves out of HLR area. Both are part of single MSC.

The VLR database contains information about all the mobile subscribers currently located in an MSC service area.

Thus there is one VLR for each MSC in a network. The VLR temporarily stores subscription information

The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. It acts as a permanent store for a person’s subscription information until that subscription is canceled. The informationstored includes:· Subscriber identity· Subscriber supplementary services· Subscriber location information· Subscriber authentication information