Question

Why is VLR regarded as a distributed HLR? What particulars about mobile will you like to keep in the VLR data base?

Answer 1

Before proceeding to the question that why VLR is regarded as a distributed HLR, we first should know what actually is HLR and VLR.

HLR stands for Home Location Register that is a database used for permanently storing data/information about a subscriber/customer such as the mobile number, activated services on the user's mobile number, whether the mobile number has been ported to some other network, etc.

VLR, on the other hand, stands for Visitor Location Register is kind of similar database/server as that of a HLR but it actually stores the data/information about a subscriber/customer who is moving from one location to another location. In simple words, it stores information about the location of the subscriber when the user gets out of the coverage area of their own local HLR.

Now, VLR is regarded as a distributed HLR because as already told, it holds a copy of the HLR information/data stored about the subscriber when the user moves out of the coverage area of their own local HLR. We use the term distributed here because, as we know that different users may move/migrate from one location to other different locations, hence they get distributed to different locations and so does the information in the VLR. In simple words, the VLR database then acts as a HLR of some other location (to which the user has moved), that is it acts as HLR distributed to some another different location.

The particulars about mobile that would be kept in the VLR database are as follows:

1. Mobile subscriber Roaming number (MSRN)
2. Subscriber's phone number
3. Service type (services that the subscriber has enrolled and is allowed to access)
4. Current location
5. HLR address Ciphering keys
6. Cost/Billing information
7. International Mobile Subscriber Identity (IMSI)
8. GPRS information or simply the access point subscribed
9. Temporary Mobile Subscriber Identity (TMSI)

Thanks!