Home Location Register


Home Location Register (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 Home Location Register 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 Home Location Register 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 Home Location Register record. The Home Location Register 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:

The Home Location Register 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 is often integrated to the Home Location Register

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