HLR

HLR (home location register)

A database residing in a local wireless network that contains service profiles and checks the identity of a local subscriber. (Cingular)

The Home Location Register or HLR is a central database that contains details of each mobile phone subscriber that is authorized to use the GSM core network.

More precisely, the HLR stores details of every SIM card issued by the mobile phone operator. Each SIM has a unique identifier called an IMSI which is one of the primary keys to each HLR record.

The next important items of data associated with the SIM are the telephone numbers used to make and receive calls to the mobile phone, known as MSISDNs. The main 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 HLR record.

Examples of other data stored in the HLR in a SIM record is:

* GSM services that the subscriber has requested or been given
* GPRS settings to allow the subscriber to access packet services
* Current Location of subscriber (VLR and SGSN)