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Home Location Register (HLR)

The HLR is a database used forstorage and management of subscriptions. The HLR is considered the most

important database, as itstores permanent data about subscribers, including a subscriber's service profile, location

information, and activity status. When an individual buys a subscription in the form of SIM, then all the information

about this subscription is registered in the HLR of that operator.

The HLR is the reference database for subscriber parameters. Actually HLR Having all

the detail like customer ID, customer number, billing detail and for prepaid with

I intelligent network its has detail of current recharge of prepaid user so far its is very 

comple! but i "ust make it in simple word for you.

 #arious identification numbers and addresses are stored, as well as authentication

parameters. This information is entered into the database by the network provider when

a new subscriber is added to the system. The HLR database contains the master

database of all the subscribers to a $%& 'L&.

The data it contains is remotely accessed by all the &%(s and the #LRs in the network 

and, although the network may contain more than one HLR, there is only one database

record per subscriber ) each HLR is therefore handling a portion of the total subscriber

database.

The subscriber data may be accessed by either the I&%I or the &%I%* number. The

data can also be accessed by an &%( or a #LR in a different 'L&, to allow inter+

system and inter+country roaming.

The asic 'arameters stored in the HLR are listed below-

• %ubscriber I* I&%I and &%I%*/

• (urrent %ubscriber #LR (urrent Location/

• %upplementary %ervices %ubscriber to (aller Tone, &issed (all Alert, Any 0ther %ervices etc./

• %ubscriber %tatus Registered or *eregistered/

•  Authentication 1ey and A2( 3unctionality 

• &obile %ubscriber Roaming umber

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• GSM services that the subscriber has requested or been given.

• GPRS settings to allow the subscriber to access packet services.

• Current location of subscriber (VR and serving GPRS support node!SGS"#.

• Call divert settings applicable for each associated MS$S%".

 Visitor Location Register (VLR)

The VLR is a database that containstemporary information about subscribers that is needed by the MSC in order

to service visiting subscribers. The VLR is always integrated with the MSC. When a mobile station roams into a new

MSC area, the VLR connected to that MSC will request data about the mobile station from the HLR. Later, if the

mobile station makes a call, the VLR will have the information needed for call setup without having to interrogate the

HLR each time.

The #LR contains a copy of most of the data stored at the HLR. It is, however,

temporary data which e!ists for only as long as the subscriber is 4active5 in the

particular area covered by the #LR.

The #LR database will therefore contain some duplicate data as well as more precise

data relevant to the subscriber remaining within the #LR coverage here coverage

means status of customer of last lac location area code updation /

The #LR provides a local database for the subscribers wherever they are physically 

located within a 'L&, this may or may not be the 4home5 system. This function

eliminates the need for e!cessive and time+consuming references to the 4home5 HLR 

database.

The additional data stored in the #LR is listed below-

6. Location Area Identity LAI/

7. Temporary &obile %ubscriber Identity T&%I/

8. &obile %tation Roaming umber &%R/

9. &obile status busy:free:no answer etc./

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Location Area Identity 

(ells within the 'ublic Land &obile etwork 'L&/ are grouped together into

geographical areas. ;ach area is assigned a Location Area Identity LAI/, a location area

may typically contain 8< cells.

;ach #LR controls several LAIs and as a subscriber moves from one LAI to another, the

LAI is updated in the #LR. As the subscriber moves from one #LR to another, the #LR 

address is updated at the HLR.

Temporary Mobile Subscriber Identity (TMSI)

The #LR controls the allocation of new Temporary &obile %ubscriber Identity T&%I/

numbers and notifies them to the HLR. The T&%I will be updated fre=uently, this

makes it very difficult for the call to be traced and therefore provides a high degree of 

security for the subscriber.

The T&%I may be updated in any of the following situations-

• (all setup.

• 0n entry to a new LAI.

•

0n entry to a new #LR.

Mobile Subscriber Roaming Number

 As a subscriber may wish to operate outside its 4home5 system at some time, the #LR 

can also allocate a &obile %tation Roaming umber &%R/. This number is assigned

from a list of numbers held at the #LR &%(/. The &%R is then used to route the call

to the &%( which controls the base station in the &%s (urrent location.

The database in the #LR can be accessed by the I&%I, the T&%I or the &%R. Typically 

there will be one #LR per &%(.