!!! Overview
[{$pagename}] ([HLR]) is a central [database] that contains details of each mobile phone subscriber that is authorized to use the [GSM] core network. 


There can be several logical, and physical, [HLRs] per [Public Land Mobile Network] ([PLMN]), though one international mobile subscriber identity ([IMSI])/[MSISDN] pair can be associated with only one logical [HLR] (which can span several physical nodes) at a time.

The [{$pagename}] store details of every [SIM] card issued by the specific [Mobile Network Operator]. Each [SIM] has a unique identifier called an [IMSI] which is the primary key to each [{$pagename}] record.

Another important item of [data] associated with the [SIM] are the [MSISDNs], which are the [Phone Number] used by [Mobile Devices] to make and receive calls. The primary [MSISDN] is the number used for making and receiving voice calls and [SMS], but it is possible for a [SIM] to have other secondary [MSISDNs] associated with it for fax and [data] [Communication]. Each [MSISDN] is also a primary key to the [{$pagename}] record. The [{$pagename}] [data] is stored for as long as a [subscriber] remains with the [Mobile Network Operator].

[Examples] of other [data] stored in the [HLR] against an [IMSI] record is:
* [GSM] services that the subscriber has requested or been given.
* [GPRS] settings to allow the subscriber to access packet services.
* [Visitor Location Register] ([VLR]) Current location of subscriber ([VLR] and serving [GPRS] support node/SGSN).
* [Call Diversion] settings applicable for each associated [MSISDN].
The [{$pagename}] is a system which directly receives and processes MAP transactions and messages from elements in the [GSM] network, for example, the location update messages received as mobile phones roam around.

The [International Mobile Equipment Identity Database] ([IMEI DB]) which list of [Mobile Device] identified by their [IMEI] which are to be banned from the network or [monitored|Monitoring] is often integrated to the [{$pagename}]

!! More Information
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