Overview#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 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 telephone numbers used by mobile phones 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 calls. 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.
- 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 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